How come I rarely hear "desu" when someone speaks in Japanese?

Question:

Ok, for starters, I have not been studying Japanese very long. But so far, it seems like every time I say a sentence in Japanese, I have to end it with "desu". But when I watch anime or hear someone speak Japanese, they only use "desu" about 30% of the time even though it means the same thing. Does it have something to do with being formal/informal or something?

Answer:

Yes, desu is used for formal.

And they rarely talk in formal form in anime. That's why. Simple.