What is a code validator? (HTML)

Question

After getting tons of suggestions to use it, why is a code validator so important? Just a beginner here sorry.

Answer 1

Validator can help you to discover mistakes in your code, broken links etc. Although browsers are mostly able to render even invalid html, it is much better to learn to do it right. The errors in html can cause problems to some browsers, your client side scripts can have unexpected results or it may be more difficult to extract (scrape) the page content.
Example of a validator:
https://validator.w3.org/

Answer 2

Its when a program helps check your code and tells you if there's issues.