for loop

Describe the 3 parts of a for loop, and how changing them changes the output of a for loop.
One of the parts is the parentheses, if you do have them it will say build failed.The second part of the loop is the initialize and if you don't have that then it will say build fail and have bugs.The last part of is the increase and the decrease and if you don't have that  it wont add or subtract