TI-Basic 89 Programming/Conditional Functions

If
If, Control(F2):1 is a command which will determine whether or not the next line of code is executed.

If...Then...EndIf
If...Then...EndIf, Control(F2):2:1 is a group of commands which will determine whether or not a block of code is executed.

If...Then...Else...EndIf
If...Then...Else...EndIf, Control(F2):2:2 is a group of commands which will determine which of two blocks of code is executed.

ElseIf...Then
ElseIf...Then, Control(F2):2:3 is a command in which could be used to add more than two code blocks in If...Then...EndIf code.