> ## Documentation Index
> Fetch the complete documentation index at: https://gcore.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Add an SSL certificate to deliver content over HTTPS

## What is an SSL certificate?

An SSL certificate is a unique digital signature for your website that verifies the authenticity of your domain and allows you to configure the HTTPS protocol for the site. This protocol provides a secure connection between a client and a server. It is essential when sensitive information is being transferred, such as during financial transactions. Learn more about SSL certificates in our [Learning article](https://gcore.com/learning/what-are-ssl-certificates).

If you want to deliver content using our CDN via secured HTTPS protocol, you need to add an SSL certificate for your CDN resource's [custom domain](/cdn/cdn-resource-options/general/create-and-set-a-custom-domain-for-the-content-delivery-via-cdn).

**Note** : You can only attach one certificate per CDN resource.

## SSL certificate types in Gcore

In Gcore, two types of SSL certificates are available:

1. Your own SSL certificate. You can issue a certificate for the custom domain in the format, e.g., cdn.example.com from a third-party company and add its data to the Gcore Customer Portal. Either do so during [CDN resource creation](/cdn/ssl-certificates/configure-your-own-ssl-certificate#method-1-add-ssl-certificate-during-cdn-resource-creation) or [add it later](/cdn/ssl-certificates/configure-your-own-ssl-certificate#method-2-add-ssl-certificate-for-an-existing-cdn-resource).

2. Free Let's Encrypt certificate. You can issue a free Let's Encrypt certificate for your custom domain. All data will be added automatically by Gcore. Either do so during [CDN resource creation](/cdn/ssl-certificates/configure-lets-encrypt-certificate#during-resource-creation) or [add it later](/cdn/ssl-certificates/configure-lets-encrypt-certificate#for-created-resource).