What does nonce mean? I'm trying to learn how litecoins work (and learn new programming language at same time by writing a crappy little miner).

I'm stuck with getdata. Here http://litecoin.info/wiki/Scrypt 
it says that data is 160 characters long. But its not. Its quite a bit longer than that.

So my questions are:


1.) What is nonce and how do I use it?
2.) What is bits?
3.) What are all the 0's after the bits.


EDIT: Ok, I think I have to use just first 160 characters of data and ignore the rest. Correct?
A nonce is just a value that you keep changing in the hope that after you hash all the data the hash will be less than the target value. See https://en.bitcoin.it/wiki/Block_hashing_algorithm (litecoin is similar only uses scrypt instead of sha256 hash function.)