Originally Posted by akcae

Most banks I've dealt with display two types of balances when checking your account online:

Current balance: net of all credits and debits to the account, in full amounts, regardless of what has actually cleared or made available. This can also show your actual balance as of beginning of the current business day (so-called hard-posted balance);
Available balance: net of all credits and debits to the account, showing only actually available funds. Most banks will "hold" a deposit until it clears the issuing bank (about 24hrs) but by law must make the first $100 of any deposit made out of checks (and ALL of cash) available immediately.

Knowing the difference between these will save you from bouncing checks or having your electronic payments returned.