FOIL
From AoPSWiki
FOIL, standing for first, outside, inside, last, is a mnemonic device for remembering the distributive property when two binomials are multiplied.
Here is an example.
First we multiply the first terms 
Then, the outside terms 
Next, the inside terms 
.
Finally, we multiply the last terms 
Thus, our answer is 
, which, when simplified, gives us a final answer of 
.
