No HTML allowed at all? (in posts)

Hey,

I have this website where visitors can submit something that will get posted automatically (not on the frontpage, but on another page)..

There’s one flaw about this: If somebody spams on my page, it will make a link, which is something I don’t want. I don’t need any HTML at all, just plain text.

Is there something I can edit in my code that will remove all the HTML? I don’t need HTML in the real posts too, except for maybe Bold and Italic.

How could I achieve this?

(It’s not just comments by the way, real posts aswell. I do need my HTML in my pages though.)

Thanks