1. The initialization: `var i = 0;` - This code runs only once at the start of the loop. It's usually used to declare the counter variable (with `var`) and initialize the counter (in this case it is set to 0).
2. The condition: `i < 5;` - The loop will run as long as this is `true`. That means that as soon as `i` is equal to 5, the loop will stop looping. Note that the inside of the loop will never see `i` as 5 because it will stop before then. If this condition is initially `false`, the loop will never execute.
3. The increment: `i++` - This code is run at the end of each loop. It's usually a simple increment (`++` operator), but can really be any mathematical transformation. It is used to move the counter (`i`) forward (`++`), backwards (`--`), or some other form of incrementation.