This is the simplest paper airplane that you can make with a piece of paper.
Glimpse of the Result:
Take a rectangular piece of paper. A little thick paper is better as this well help the plane to fly.
Fold the paper across its length in half to make the main crease.
Fold each top towards the main crease to form a triangle at the top.
Fold the paper inwards along the main crease.
Open the flap of the paper from the side towards the crease.
Repeat the above step for the next side as well to get the structure shown below.
Hold the center/main crease from the bottom to start flying the plane.