Can Someone Explain Verb Bases?

Hi everyone!
Well, in my attempt to teach myself Japanese (seeing as there's no teachers around here), I came across things called ''verb bases''. Now I know that formal verbs take ''-Masu'', ''Masen'', ''-Mashita'' and ''-masen deshita'' for their conjugations. So I'm assuming that bases are solely for Informal purposes. Is this correct?
Secondly, what is the purpose of having all those bases? Do bases change the meaning of the verb in some way or something? I know there's rules considering the endings of the verbs and things. I just need to understand the changes that occur. Please try and keep it simple, I've just started learning. Thanks for any help!

Arigatou Gozaimasu!

Some textbooks explain things differently from others - can you please list what your textbook refers to as "verb base"?

I am assuming that they mean the "stem" or "root" of the verbs themselves.

For example, for the verb "taberu/tabemasu," meaning "to eat," the polite FORM is "tabemasu," and the informal form is "taberu," while the stem/base of the verb is "tabe-" (followed by different verb endings to express different things).

Did I guess it right?

Now I know what you mean by "verb base" - you must have found it in sites like this one, right?
http://www.freejapaneselessons.com/lesson08.cfm

If you look at this page, you can tell how they are used; "verb bases" are different conjugations of the verb stem, and these different forms are used depending on what words with different meanings get connected to them.

This way of explaining Japanese language grammar is very traditional grammar-focused and is not the easiest way when teaching to non-native speakers of Japanese as against teaching young Japanese people - I have seen other textbooks which do not explain grammar this intensively from the start, using those "base" thing, which can be easier to get into... so it would also help you understand better if you could find a more dialogue-based learning material as well.