Hey DD, I've just got a real quick question. When searching for a hosting company for my website, I always come accross things like MySQL Databases: Unlimited! or MySQL Databases: 30. What exactly does that mean? does it mean that i can only use the mysql_query("Create database") function 30 times?

No, not at all.

It means you can have 30 databases... like 30 different spreadsheeets.

You could have a database for your chatroom, a database for your forum, and another one for your email setup. That would be 3.

Some hosts will only give you 1.

However, while I think there CAN be limits set on database size, they certainly can be large, and I don't know of any hosts that limit size. For my forum, for example, it's about 30mb right now, of just text. MySQL databases are certainly capable of being huge. Some not quite so nice hosts might limit the size of databases, in which case the number of them would matter.

In the end, the only reason for more than one database is to keep things seperate. Each database contains tables, then contains rows within those, and data in each cell of each row.
For example:
db: forum
table: members
row: 1
cell "username": djr33

You would probably want totally different things in different databases, but the point is integration. You certainly don't want to be calling from more than one database from the same php script.

anyway, unlimited may be better, but 30 is surely enough, unless you have some insane need for lots of data storage.