If...ElseIF....Else

IF

IF Condition
  do Visual Logic Sub-Block

Tests the condition and if this is successful obeys the lines of Visual Logic in the sub-block.

ELSE IF

ELSEIF Condition
    do Visual Logic Sub-Block

If and only if none of the preceding IF / ELSEIF lines in a continuous sequence at this indent level have been successful ELSEIF tests the condition and if this is successful obeys the lines of Visual Logic in the sub-block.

ELSE

ELSE
  do Visual Logic Sub-Block

If and only if none of the preceding IF / ELSEIF lines in a continuous sequence at this indent level have been successful obeys the lines of Visual Logic in the sub-block without testing any further conditions.

You can find a simulation example on IF/ ELSEIF here: IF.s8