This blog will refer to IF formulas quite a bit, and for good reason--they're important for doing almost anything interesting in Excel! But it's first important to realize that the whole world of conditional statements relies on a foundational concept that has traditionally been the province of philosophers: the concept of TRUE and FALSE.
Microsoft Excel doesn't treat a cell containing the words "TRUE" or "FALSE" as regular ol' text strings. These are values--if we want to get technical about it, they are called Boolean values. They have special properties that we can use in mathematical formulas (TRUE has a number value of 1 and FALSE has a number value of 0), logical functions (AND, OR), and conditional functions (IF).
Let's look at a few examples:
All of the examples on the left yield a Boolean value of TRUE. These include just typing the word "TRUE" (not case sensitive), typing a true equality (1=1) after an equals sign, typing a true inequality (5>4) after an equals sign, or evaluating a true logical function (AND(1=1,2=2)). See the righthand column for the counterparts of each TRUE example that evaluate to FALSE.