system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How does an SSL certificate keep my website safe?
gpt
Imagine you have a friend and that friend has a friend.

You don't know your "friend of a friend", but your friend vouches for them, and says they're a good person.

Your friend is a really good person, so you trust your friend when they say that this other person is a really good person.

There are certain "certificate authorities" in the world. They're groups who everybody has agreed are reputable and are allowed to hand out certificates. Your computer trusts those certificate authorities by default. They're like your good friend that you trust.

An SSL certificate is a "signed certificate"(like a signed letter) from your trusted friend that says "This website that you're connecting to really is who they say they are."

When you try to connect to a website, the site responds with the certificate they have to identify that the site is who they say they are.

Websites are just files on certain really fast computers(called servers). The really fast computers' only point is to hand out files.

But anyone could set up a similar computer running a fake website that looks the same and try to make people think it was real site, and try to collect people's information when they entered it into the site.

In the address bar of browsers like Chrome, if you click the lock, you can see the certificate information provided by the site, to make sure that the site is who they say they are.