In most computer applications the IF function operates in the fashion IF/THEN/ELSE:
IF a certain condition is met THEN perform some action, ELSE perform a different action (which could be to take no action at all).
For example:
=IF(A+B>=100,"Target Met","Target not met")
IF A+B is greater than or equal to 100
THEN display, "Target met",
ELSE display, "Target not met".