When someone visits your website, their browser and your server exchange information back and forth. Without encryption, this conversation happens in plain text, meaning anyone monitoring the network could read everything: login credentials, personal messages, payment information, all of it.
An SSL certificate solves this by enabling HTTPS, which encrypts all data between the browser and your server. The little padlock icon in your browser’s address bar? That’s telling you the connection is encrypted and secure.
For years, getting an SSL certificate meant paying a certificate authority annually and going through a tedious manual setup process. Then Let’s Encrypt came along and changed everything. It’s a free, automated certificate authority that exists for one purpose: making encrypted connections the default across the entire web.