First
Outer
Inner
Last
it is a way of remembering how to multiply binomials
it tells which terms to multiply
example
(x+3)(x+4)
First (multiply first terms)
x times x=x²
Outer (multiply outer terms)
x times 4=4x
Inner (multiply inner terms)
3 times x=3x
Last (multiply last terms)
3 times 4=12
now add them all
x²+4x+3x+12
x²+7x+12
that is what FOIL is