Probably the easiest knot on the planet...
-and even though it's often done wrong..!
I choose ( for the clarity of it ) to bind a green and a blue rope. That's a model you'll see often in this homepage.
1/ Two ropes.
2/ Pull the blue rope over the green one, and
then under.
Lay the green rope over the blue one.
3/ Now lay the blue rope 'back', to form a bow.
Lay the green rope over the blue rope, under
the blue one, and finally over the blue rope.
When you pull the ends you will tighten the knot, and
that's it !
This is what it looks like in the real world ( hope you'll forgive me for the fact, that the green rope has faded to a white one )...