What Is SSL? SSL Certificates and HTTPS Explained
The padlock in your browser is SSL at work. This guide explains what SSL is, how it works, SSL vs TLS, the types of SSL certificates, why every website needs one, and how to get one.
SSL is the technology that encrypts the connection between a browser and a website, turning a readable connection into a private one, and it is why you see a padlock and https in your address bar. Today it is a baseline requirement: browsers label sites without it as Not Secure, and Google treats HTTPS as a ranking signal. This guide explains what SSL is (and how it relates to TLS), why every website needs it, how the SSL handshake works, what an SSL certificate is and its types, how HTTPS and the padlock fit together, how to get a certificate (often free), and the common errors to avoid. Building a site? Appy Pie AI includes free SSL automatically.
What This Guide Covers
- What SSL is (and SSL vs TLS)
- Why every website needs it
- How SSL works (the handshake)
- SSL certificates & their types
- SSL, HTTPS & the padlock
- How to get SSL & fix errors
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Get Started FreeTL;DR Quick Summary
SSL (Secure Sockets Layer) encrypts the connection between a browser and a website so data cannot be read or altered in transit; it is why you see a padlock and https. The modern version is technically TLS (use TLS 1.2 or 1.3), but everyone still says SSL. It works via the TLS handshake: the server presents an SSL certificate with its public key, the browser verifies it against a trusted Certificate Authority, and they agree a session key to encrypt the visit. Certificates come in DV, OV and EV validation levels and single, wildcard or multi-domain coverage; a free DV certificate (for example from Let’s Encrypt) suits most sites. Every website needs SSL for security, trust and SEO. Managed website builders provision and renew it automatically.
Launch a Secure Site →Table of Contents
Jump to any section: what SSL is, why every website needs it, how SSL works (the handshake), SSL vs TLS, what an SSL certificate is, the types of certificates, SSL and HTTPS and the padlock, how to get an SSL certificate, common SSL errors, getting free SSL with no code, an SSL setup checklist, and the mistakes to avoid, plus an FAQ.
- What Is SSL?
- Why Every Website Needs SSL
- How SSL Works: The Handshake
- SSL vs TLS: What Is the Difference?
- What Is an SSL Certificate?
- Types of SSL Certificates
- SSL, HTTPS and the Padlock
- How to Get an SSL Certificate
- Common SSL Errors and How to Fix Them
- Get Free SSL With a No-Code Website Builder
- SSL Setup Checklist
- Common SSL Mistakes to Avoid
- Frequently Asked Questions
What Is SSL?
SSL (Secure Sockets Layer) is the technology that encrypts the connection between a web browser and a website, so the data that passes between them, passwords, card numbers, form entries, cannot be read or tampered with by anyone in between. It is what turns a plain, readable connection into a private one, and it is why you see a padlock and “https” in your browser’s address bar.
Strictly speaking, the modern version of SSL is called TLS (Transport Layer Security), but almost everyone still says “SSL”, and the certificates that enable it are still called SSL certificates. When people talk about SSL today, they mean the encryption that protects a website.
SSL does three jobs at once: it encrypts data so it stays private, it authenticates the site so you know you are really talking to who you think, and it protects integrity so the data is not altered on the way. This guide explains how SSL works, SSL vs TLS, what an SSL certificate is and its types, how HTTPS fits in, and how to get SSL on your own site. Building a website? Appy Pie AI includes free SSL automatically.
Why Every Website Needs SSL
SSL is no longer optional. It protects your visitors, earns their trust, and is now expected by both browsers and search engines.
It protects sensitive data
Without SSL, everything sent between a visitor and your site travels as plain text that anyone on the network can read. SSL encrypts it, so logins, payments and personal details stay private.
It builds trust and avoids warnings
The padlock and HTTPS signal a secure site. Just as importantly, modern browsers actively label sites without SSL as “Not Secure”, which scares visitors away before they even see your content.
It helps SEO
Google has used HTTPS as a ranking signal since 2014, and a secure site is a baseline expectation for ranking well. SSL is now part of technical SEO, not a nice-to-have.
How SSL Works: The Handshake
SSL secures a connection through a quick exchange called the TLS handshake, which happens in milliseconds before any real data is sent.
The certificate and public key
When you visit a secure site, the server sends its SSL certificate, which contains its public key and is signed by a trusted Certificate Authority. Your browser checks the certificate is valid and trusted before continuing.
Asymmetric to agree, symmetric to talk
The browser and server use the public and private key pair (asymmetric encryption) to securely agree on a shared session key. From then on they use that single session key (fast symmetric encryption) to encrypt everything for the rest of the visit.
A private, verified channel
The result is a connection that is encrypted (private), authenticated (you are talking to the real site), and tamper-evident (data cannot be quietly altered). All of it happens automatically, in a fraction of a second.
SSL vs TLS: What Is the Difference?
SSL and TLS are often used interchangeably, but technically TLS is the newer, more secure successor to SSL. The old SSL versions are deprecated; every secure site today actually uses TLS.
| Protocol | Status | Notes |
|---|---|---|
| SSL 2.0 / 3.0 | Deprecated and insecure | The original protocols, now disabled everywhere for known vulnerabilities |
| TLS 1.0 / 1.1 | Deprecated | Retired by browsers; should no longer be used |
| TLS 1.2 | Widely supported | The long-standing secure baseline, still perfectly valid |
| TLS 1.3 | Current best | Faster and more secure; the modern standard |
The takeaway: people say “SSL” and “SSL certificate” out of habit, but you want your server using TLS 1.2 or 1.3. The certificate you buy or get for free is the same either way, it is the protocol version that matters.
What Is an SSL Certificate?
An SSL certificate is a small data file installed on your web server that makes the secure connection possible and proves your site’s identity. It is what a Certificate Authority issues to you.
What it contains
A certificate holds your domain name, your public key, the issuing Certificate Authority, and validity dates, all digitally signed so browsers can verify it has not been forged or altered.
The Certificate Authority
A Certificate Authority (CA) such as Let’s Encrypt, DigiCert or Sectigo verifies you control the domain (and, for higher tiers, your organisation) before issuing the certificate. Browsers trust certificates only from recognised CAs.
The chain of trust
Your certificate links back to the CA’s root certificate through a chain of trust that browsers already trust. That chain is why a visitor’s browser accepts your certificate automatically, with no warning.
Types of SSL Certificates
SSL certificates differ in how much identity they validate and how many domains they cover. Choose based on your site type and how much visible trust you need.
| Type | Validates | Best for |
|---|---|---|
| DV (Domain Validated) | Control of the domain only | Blogs, small sites, most websites; issued in minutes and often free |
| OV (Organization Validated) | Domain plus the organisation | Business and company sites wanting verified identity |
| EV (Extended Validation) | Rigorous organisation vetting | Banks, large e-commerce and enterprises needing the highest assurance |
| Wildcard | A domain and all its subdomains | Sites with many subdomains (shop., blog., app.) |
| Multi-domain (SAN) | Several different domains | Organisations securing multiple sites with one certificate |
For most websites a free DV certificate is all you need; the encryption is identical. OV and EV add verified identity, not stronger encryption.
SSL, HTTPS and the Padlock
SSL and HTTPS are two sides of the same thing. HTTPS is simply HTTP running over an SSL/TLS-encrypted connection.
HTTP vs HTTPS
Plain HTTP sends data in the clear over port 80. HTTPS wraps it in TLS encryption over port 443, so the same web traffic becomes private. The “S” stands for secure.
What the padlock means
The padlock in the address bar means the connection is encrypted with a valid certificate. It does not certify the site is trustworthy or legitimate in intent, only that the connection is private, so treat it as necessary, not sufficient.
Mixed content
If an HTTPS page loads some assets (images, scripts) over insecure HTTP, that is “mixed content”, and browsers warn or block it. To keep the padlock, every resource on the page must load over HTTPS.
How to Get an SSL Certificate
Getting SSL is easier and cheaper than most people expect, often free and automatic. Choose the path that matches how your site is hosted.
Free certificates (Let’s Encrypt)
Let’s Encrypt issues free DV certificates that auto-renew every 90 days. Most modern hosts and platforms integrate it, so you get SSL with a click or automatically.
Through your host or CDN
Many web hosts and CDNs (such as Cloudflare) provide free SSL and handle installation and renewal for you. This is the simplest route for most site owners.
Paid certificates from a CA
For OV or EV certificates, or a warranty and support, you buy from a Certificate Authority or reseller, complete their validation, and install the certificate on your server.
Common SSL Errors and How to Fix Them
Most SSL problems produce a clear browser warning. Here are the ones you will actually see and what causes them.
Certificate expired
An expired certificate (NET::ERR_CERT_DATE_INVALID) is the most common issue. Renew it, or use an auto-renewing certificate so it never lapses.
Name mismatch
If the certificate does not match the domain being visited (ERR_CERT_COMMON_NAME_INVALID), for example www vs non-www, reissue it to cover the correct hostnames.
Untrusted or self-signed
A self-signed certificate, or one from an untrusted CA (ERR_CERT_AUTHORITY_INVALID), triggers a warning. Public sites must use a certificate from a recognised Certificate Authority.
Mixed content
If the padlock is missing on an HTTPS page, an asset is loading over HTTP. Update those URLs to HTTPS to restore a fully secure page.
Get Free SSL With a No-Code Website Builder
If you build your site on a managed platform, SSL is one thing you never have to think about, it is provisioned, installed and renewed for you.
What a no-code builder handles
Platforms like Appy Pie AI include a free SSL certificate on every site, served over HTTPS by default, with renewal handled automatically, so your visitors always see the padlock and you never touch a certificate file or a server config.
What is still worth knowing
Even with SSL handled, it helps to understand what it does: SSL secures the connection, but it does not replace strong passwords, secure forms or good privacy practices. It is the foundation of a trustworthy site, not the whole of it.
Launch a secure, HTTPS site with free SSL built in on Appy Pie AI website builder.
SSL Setup Checklist
Whether you install SSL yourself or use a managed platform, run through this list to make sure your site is fully secure.
- Install a valid certificate from a trusted Certificate Authority (free DV is fine for most sites).
- Serve every page over HTTPS, not just the checkout or login.
- Redirect all HTTP to HTTPS so there is only one secure version of each page.
- Fix mixed content by loading every image, script and style over HTTPS.
- Use TLS 1.2 or 1.3 and disable old SSL and early TLS versions.
- Enable auto-renewal so the certificate never expires.
- Confirm the padlock shows on every page, and update internal links to HTTPS.
On a managed builder most of this is automatic; on a self-hosted site it is your checklist to work through.
Common SSL Mistakes to Avoid
Most SSL trouble comes from a few avoidable mistakes. Steer clear of these and your site stays secure and warning-free.
The pattern is familiar: leaving some pages on HTTP instead of securing the whole site, letting a certificate quietly expire, ignoring mixed-content warnings so the padlock disappears, running outdated SSL or early TLS versions, self-signing a certificate on a public site so browsers reject it, and assuming SSL alone makes a site completely secure. Do the opposite, secure every page, auto-renew, fix mixed content, use modern TLS, use a trusted CA, and pair SSL with good security habits, and your site stays private and trusted.
Do this
- Serve every page over HTTPS site-wide
- Redirect all HTTP to HTTPS
- Auto-renew so the certificate never expires
- Fix mixed content (all assets over HTTPS)
- Use TLS 1.2 or 1.3
- Use a trusted CA (free DV is fine)
Avoid this
- Leaving some pages on HTTP
- Letting the certificate expire
- Ignoring mixed-content warnings
- Running outdated SSL or early TLS
- Self-signing a public site’s certificate
- Assuming SSL alone makes a site fully secure
Launch a Secure Site With Free SSL
You should not have to wrangle certificates to get a padlock. Build on a managed platform that serves your site over HTTPS with a free SSL certificate installed and auto-renewed, so it is secure from the first visitor.
Get Started Free Read: How to Make a WebsiteFrequently Asked Questions
What is SSL?
SSL (Secure Sockets Layer) is the technology that encrypts the connection between a web browser and a website, so data like passwords, card numbers and form entries cannot be read or tampered with in transit. It is why you see a padlock and https in the address bar. Technically the modern version is called TLS (Transport Layer Security), but everyone still says SSL. It does three things at once: encrypts data for privacy, authenticates the site so you know it is genuine, and protects integrity so data is not altered on the way.
What is an SSL certificate?
An SSL certificate is a small data file installed on a web server that enables the encrypted HTTPS connection and proves the site’s identity. It contains the domain name, the site’s public key, the issuing Certificate Authority and validity dates, all digitally signed. A Certificate Authority (like Let’s Encrypt, DigiCert or Sectigo) verifies you control the domain before issuing it, and the certificate links back to a trusted root through a chain of trust, which is why browsers accept it automatically without showing a warning.
What is the difference between SSL and TLS?
TLS (Transport Layer Security) is the newer, more secure successor to SSL (Secure Sockets Layer). The original SSL versions (2.0 and 3.0) are deprecated and insecure, and early TLS (1.0 and 1.1) is retired too; modern secure sites use TLS 1.2 or 1.3. People still say SSL and SSL certificate out of habit, but the actual protocol securing your site should be TLS 1.2 or 1.3. The certificate itself is the same; what matters is that your server uses a current TLS version.
How does SSL work?
SSL secures a connection through the TLS handshake, which happens in milliseconds. When you visit a secure site, the server sends its SSL certificate containing its public key, and your browser verifies it is valid and issued by a trusted Certificate Authority. The browser and server then use that public/private key pair (asymmetric encryption) to securely agree on a shared session key, and from then on they encrypt everything with that fast session key (symmetric encryption). The result is a connection that is private, authenticated, and tamper-evident, set up automatically before any real data is sent.
Why does my website need SSL?
Three reasons. Security: without SSL, data between your visitors and your site travels as plain text anyone on the network can read, so logins and payments are exposed. Trust: browsers now label sites without SSL as Not Secure, which drives visitors away, while the padlock and HTTPS reassure them. SEO: Google has used HTTPS as a ranking signal since 2014, so a secure site is a baseline expectation for ranking. SSL is now a requirement for any legitimate website, not an optional extra.
What is the difference between HTTP and HTTPS?
HTTP (Hypertext Transfer Protocol) sends data in plain text over port 80, so anyone in between can read it. HTTPS is the same protocol running over an SSL/TLS-encrypted connection on port 443, so the traffic is private and tamper-evident. The S stands for secure. HTTPS is what gives you the padlock in the browser, and it is now the standard: browsers flag plain HTTP pages as Not Secure, and Google prefers HTTPS in rankings. To serve HTTPS you install an SSL/TLS certificate on your site.
What are the types of SSL certificates?
By validation level: DV (Domain Validated) confirms you control the domain, is issued in minutes and is often free, and suits most websites; OV (Organization Validated) also verifies your organisation, for business sites; and EV (Extended Validation) involves rigorous vetting, for banks and large enterprises. By coverage: single-domain covers one domain, wildcard covers a domain and all its subdomains, and multi-domain (SAN) covers several different domains with one certificate. The encryption is identical across types; OV and EV add verified identity, not stronger security.
How do I get an SSL certificate?
The easiest and cheapest route is a free certificate from Let’s Encrypt, which issues DV certificates that auto-renew every 90 days and is integrated into most hosts and platforms. Many web hosts and CDNs (such as Cloudflare) also provide free SSL and handle installation and renewal for you. For OV or EV certificates, or a warranty, you buy from a Certificate Authority or reseller, complete their validation, and install the certificate on your server. If you use a managed website builder, SSL is usually provisioned and renewed automatically with nothing to install.
Is SSL free?
Yes, it can be. Let’s Encrypt provides free DV (Domain Validated) certificates that auto-renew, and many web hosts, CDNs and website builders include free SSL with installation and renewal handled for you. Free certificates provide exactly the same encryption as paid ones. You pay only when you need an OV or EV certificate (which adds verified organisational identity), a warranty, dedicated support, or specific coverage like a premium wildcard. For most websites, free SSL is entirely sufficient.
Does SSL help SEO?
Yes. Google confirmed HTTPS as a ranking signal in 2014, so having SSL is part of the baseline for ranking well. Beyond the direct signal, SSL affects SEO indirectly: Chrome and other browsers label non-HTTPS sites as Not Secure, which increases bounce rate and lowers trust and engagement, both of which matter for rankings. SSL will not by itself push you to the top, but not having it is a real handicap. Treat HTTPS as a required foundation of technical SEO rather than an optional boost.
SSL: Small File, Big Job
SSL is a small certificate that does an outsized job: it keeps your visitors’ data private, proves your site is genuine, earns the trust the padlock represents, and clears a baseline Google and browsers now expect. Understand it, keep it valid, and serve every page over HTTPS. Or skip the setup entirely: build on Appy Pie AI, where free SSL is provisioned and renewed for you and every site is HTTPS by default.
Start Building Free →Build a Secure HTTPS Site With Appy Pie AI
No certificates to install, no config files. Every Appy Pie AI site ships over HTTPS with a free SSL certificate installed and auto-renewed, so you are secure and trusted from day one.
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Aasif Khan
Head of SEO and Growth Marketing Lead at Appy Pie AI with 17+ years in digital marketing, AI-powered optimization, and scalable growth strategies.
Abhinav Girdhar
Founder and CEO of Appy Pie AI. Builder of one of the world’s largest no-code and AI platforms, with 10M+ apps and websites created.