10 LET A = 1 // 1
20 FOR I = 0 TO 3 // A + 1 four times, thus 4 
30 LET A = A + 1 
40 PRINT A  // Prints the added number each time
50 NEXT I // I think this goes back in the loop (to the FOR,)

in PHP something like this

for ( $i=0; $i < 3; $i++ )
{ 
	echo $i;
}