What are the legal and illegal characters in URL/Link?

Question

What happens if there is a illegal character? Does the URL fix it self by encoding the illegal characters into something else?

Answer 1

As explained here

ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-._~:/?#[]@!$&'()*+,;=. Any other character needs to be encoded with the percent-encoding (%hh). Each part of the URI has further restrictions about what characters need to be represented by an percent-encoded word.