What Is an SSL Certificate? Definition, How It Works, Types, Do You Need It

Understanding what a SSL certificate is important if you want to secure your website and user data. This ultimate guide explains what a SSL certificate is, how it works, the various SSL types, their costs, and whether you need one.

This guide is meant for website administrators, business owners, and anyone interested in creating and maintaining a more secure online presence. Let’s begin.

What Is an SSL Certificate?

An SSL certificate (aka TLS certificate) is a digital document that ensures secure connections between a web server and a user’s browser. It encrypts this data to protect sensitive information from being intercepted by unauthorized parties. SSL stands for Secure Sockets Layer, but these certificates are also known as TLS (Transport Layer Security) certificates. Installing an SSL Certificate enables a website to switch from HTTP to HTTPS and this sends positive trust signals to users. 

What is SSL?

SSL, or Secure Sockets Layer, is a protocol designed for securing internet connections against eavesdropping, tampering, and forgery. The primary purpose of SSL is to facilitate encrypted communication between a web server and a browser. SSL was initially the standard technology for securing online transactions, data transfers, and login information.

What is TLS?

TLS, or Transport Layer Security, is the updated and more secure version of SSL that is now widely used today. The terms TLS and SSL ultimately refer to the same thing but the term SSL is more commonly used to refer to both protocols. 

What is HTTPS?

HTTPS stands for HyperText Transfer Protocol Secure. It is the secure version of HTTP which is the protocol over which data is sent between a browser and a website. HTTPS uses SSL/TLS protocols to encrypt the data traffic and protect the integrity and confidentiality of data between the user’s computer and the site. Websites using HTTPS display a padlock symbol in the browser’s address bar.

How Do SSL Certificates Work?

SSL certificates work by establishing a secure, encrypted connection between a web server and a browser. SSL certificates contain these 6 components to function:

Public Key

The public key is part of the encryption process. It is used to start a secure session with the server.

Certificate Authority’s Signature

The CA’s signature validates the certificate as genuine and trusted.

Issuer’s Details

Information about the authority that issued the SSL certificate.

Subject’s Details

Information about the website owner, including the domain name.

Validity Period

This specifies the duration for which the certificate is valid.

Serial Number

A unique identifier for the certificate.

The SSL certificate encryption process involves 5 steps.

First, when you visit a secure website, your browser requests that the server identify itself. Secondly, the server sends a copy of its SSL certificate to your browser as proof of its identity. Thirdly, the browser checks the certificate. Brower will send a message to the server if it trusts the SSL certificate. Fourthly, the server sends back a digitally signed acknowledgement, establishing an encrypted session between the server and the browser. Lastly, encrypted data is exchanged. The exchanged data is encrypted and decrypted during the SSL session.

What Are the Types of SSL Certificates?

There are 8 types of SSL certificates and these are:

What is a Domain Validated (DV) SSL Certificate?

A Domain Validated (DV) SSL Certificate is a type of SSL certificate that provides a basic level of security by verifying the ownership of the domain name. It requires the website owner to prove domain control by responding to an email or DNS record verification. This type of certificate is issued quickly due to its minimal validation process. It primarily encrypts user data during transmission.

What is an Organization Validated (OV) SSL Certificate?

An Organization Validated (OV) SSL Certificate is a type of SSL certificate that offers a higher level of security by requiring not only domain ownership verification but also validation of the organization’s identity. The issuing Certificate Authority (CA) checks the company’s details, such as its name, location, and existence.

What is an Extended Validated (EV) SSL Certificate?

An Extended Validated (EV) SSL Certificate is a type of SSL certificate that provides the highest level of security and trust by conducting thorough background checks of the organization. The validation process includes verifying the legal, physical, and operational existence of the entity. Websites with an EV certificate display a green address bar or company name in the browser.

What is a Single Domain SSL Certificate?

A Single Domain SSL Certificate is a type of SSL certificate designed to secure one fully qualified domain name or subdomain. It requires verification of domain ownership and encrypts data transmitted between the web server and the user’s browser. This type of certificate is ideal for small websites with a single service domain.

What is a Multi-Domain SSL Certificate?

A Multi-Domain SSL Certificate (a.k.a. Subject Alternative Names (SAN) SSL Certificate) is a type of SSL certificate that allows multiple domain names to be secured with a single certificate. It requires the owner to verify control over each included domain name. This type of certificate is beneficial for businesses operating multiple sites across different domain names.

What is a Wildcard SSL Certificate?

A Wildcard SSL Certificate is a type of SSL certificate used to secure a domain and an unlimited number of its subdomains. It requires verification of the main domain’s ownership and automatically applies security to any subdomain associated with it. This certificate is ideal for organizations with large websites and multiple subdomains.

What is a Unified Communications Certificate (UCC)?

A Unified Communications Certificate (UCC) is a type of SSL certificate designed to secure multiple domain names as well as multiple host names within a domain. It was originally intended for securing unified communications and collaboration services such as Microsoft Exchange and Live Communications Server. Any business that manages multiple domains and subdomains under a single certificate benefits from a UCC.

What is a Self-Signed SSL Certificate?

A Self-Signed SSL Certificate is a certificate issued by the website owner rather than a trusted Certificate Authority. This type of certificate provides the same level of encryption as other SSL certificates but lacks the validation provided by external authorities. It is commonly used in testing environments or internal networks where public trust is not required.

How Much Do SSL Certificates Cost?

SSL certificates cost $0 to $3480 per year. There are 4 factors that affect their price. The first factor is the number of domains secured (single domain, multiple domain or wildcard SSL). The second factor affecting cost is the validation level. DV certificates and EV certificates are the most expensive. The third factor is the SSL validity duration. The fourth factor is the issuing Certificate Authority. More established brands like DigiCert, Sectigo, and Comodo cost more money. Check our full guide to SSL certificate costs for a price comparison of the various types.

Can I Get SSL Certificates for Free?

Yes, you can get SSL certificates for free. Let’s Encrypt, ZeroSSL and Cloudflare are certificate authorities that provide no-cost SSL certificates. Many reputable web hosts also include free SSL certificates as part of their packages. 

Where Can I Buy SSL Certificates?

You can buy SSL certificates directly from certificate authorities (CAs). These CAs offer a variety of SSL certificates that vary by validation levels (e.g. DV, OV, EV) and the number of domains they secure. This ensures that there’s an option suitable for different security needs and website configurations.

Who Are the Certificate Authorities (CA)?

Certificate Authorities (CAs) are trusted entities that issue digital certificates like SSL/TLS certificates. The primary role of a CA is to validate the identities of entities (like organizations and websites) and to bind these identities to cryptographic keys through the issuance of certificates. 4 popular CAs include Let’s Encrypt, DigiCert, IdenTrust, and Sectigo. 

How Do I Choose an SSL Certificate?

You choose a SSL certificate by following three main criteria: the level of validation needed, the number of domains to secure, and whether you need a combination of both.

Choose Organization Validated (OV) Certificates if your business handles sensitive information and you need to verify your identity. Choose Extended Validation (EV) Certificates if you aim to maximize user trust. EV certificates are especially suitable for eCommerce sites as they display your company’s name directly in the browser’s address bar.

Choose Wildcard SSL Certificates if you need to secure all subdomains under a single domain.

Multi-Domain SSL Certificates (SAN) are best for securing multiple distinct domains and subdomains. They offer flexibility for businesses that manage several sites.

How Do I Renew My SSL Certificate?

There are 5 steps to renew your SSL certificate:

Firstly, set up reminders or enable email notifications from your certificate provider. This alerts you when it’s time to renew your certificate. Secondly, generate a Certificate Signing Request (CSR) from your hosting control panel or ask your hosting provider to generate one. Thirdly, purchase and activate your new SSL certificate from your original CA or another provider. You need to submit your CSR during the purchase process. Fourthly, validate your domain control again after purchasing your SSL certificate. This confirms that you still own the domain for which the SSL certificate is issued. Follow the instructions sent via email by your CA. Lastly, install your new SSL certificate on your server, either automatically or manually, depending on your hosting setup.

Does My Website Need an SSL Certificate?

Yes, your website does need an SSL certificate. Websites lacking an SSL certificate are perceived as less trustworthy by visitors. Modern browsers like Google Chrome and Mozilla Firefox display warning messages to users when they visit non-HTTPS sites, which indicate that the site is not secure and deters users from engaging with the site. 

SSL certificates also play a crucial role in search engine optimization (SEO). Google has confirmed that using HTTPS is a ranking factor, which means websites with SSL certificates have better organic search visibility. It’s highly recommended to immediately install an SSL certificate from the get go when setting up your website.

Are SSL Certificates Important for Securing My Website?

Yes, SSL certificates are important for securing your website. They ensure that sensitive information like passwords, credit card details, and personal data cannot be intercepted by unauthorized parties. SSL encryption also helps to protect against dangerous cyber threats such as data breaches and man-in-the-middle attacks. SSL certificates are therefore a critical component of securing your website from malicious actors. 

How Do I Install an SSL Certificate on My Website?

You install an SSL certificate on your website using cPanel. These are 7 steps. 

Firstly, log in to your cPanel dashboard by accessing your hosting account and opening the cPanel interface. Secondly, navigate to the ‘Security’ section and click on the ‘SSL/TLS’ manager. Thirdly, access SSL management by clicking on ‘Manage SSL sites’ under the ‘Install and Manage SSL for your site (HTTPS)’ option. 

Fourthly, select your domain from the dropdown menu. Fifthly, enter your certificate details, including the SSL Certificate, Private Key, and Certificate Authority Bundle (CABUNDLE) in the respective fields. Sixthly, click the ‘Install Certificate’ button to finalize the installation. Lastly, verify the installation by visiting your website with https:// to ensure the SSL certificate is active.

Can I Use a Single SSL Certificate on Multiple Websites?

Yes, you can use a single SSL certificate on multiple websites with a Multi-Domain or Subject Alternative Names (SAN) SSL certificate. This type is ideal for managing several domains or subdomains efficiently. They cover all necessary sites under one certificate instead of maintaining separate ones for each domain.

What Happens When an SSL Certificate Expires?

When an SSL certificate expires on your website, warnings such as “Your connection is not secure” or “Your connection is not private” are shown to visitors that access your site. These alerts negatively impact traffic and trust. An expired SSL certificate also means that communications between your website and its visitors are no longer encrypted. This lack of encryption exposes data exchanged on the site to potential interception by cyber threats.

Where Is the SSL Certificate Stored on My Website?

The SSL certificate for your website is stored on the web server that hosts your site. This is managed within the file system of the server. Common web server software such as Apache, Nginx, and LiteSpeed all maintain directories where these SSL certificates and their corresponding private keys are securely kept.