What is a HeadlessChrome user agent?

Here's what I get when I inspect user agents visiting my site:

Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) HeadlessChrome/92.0.4512.0 Safari/537.36
Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) HeadlessChrome/91.0.4472.114 Safari/537.36 Prerender (+https://github.com/prerender/prerender)
...

What does this prerender thing mean? What does this HeadlessChrome mean? Are all of these bots?
FYI, I am using Netlify as my hosting.

Comments

[Bramus!]

It's an instance of Chrome that is running without any visual UI. It is mainly used for testing.

More info: developer.chrome.com/blog/headless...

[Silvestar Bistrović]

Got it. But why am I seeing like dosens of those a day on my site?

[Bramus!]

Could be anything: An uptime checker, a screenshot generator, …

[Silvestar Bistrović]

Thanks for the clarification. I just needed confirmation, and now all my doubts are gone.

[Al - Naucode]

Thanks, it was a good read, bookmarked, and followed!

[Silvestar Bistrović]

Short, but sweet.