Scouts call this knot the 'Friendship knot'
But also has lots of other names like: the 'Square Knot',
The 'Success knot', the 'Rustlers knot', the 'Japanese Crown knot', the 'Chinese Crown knot' and lastly the 'Buckaroo Knot.
One of the requirements for the pioneer badge is to stop the end of the rope from fraying the term called 'Whipping'. Here is the video for how to tie 'Simple Whipping'
A nice easy way to tie to ropes together. They even can be different thickness of rope your tying together (but if there a lot different I would suggest the double sheet bend instead).
'Bowline' (pronounced "boh-linn") which is a loop tied at the end of the rope. This knot has been called the "King of knots" probably for how useful and strong it is. Some people find it easier to remember how to tie this knot by imagining the loop you make is a rabbit hole, the end of the rope is a rabbit, The rabbit jumps out the hole, It runs around the back of rope which is 'the tree', Then the rabbit jumps back down the hole
"Figure-of-eight" stopper Knot and a tougher "figure-of-eight lashing"
Its great for a tent guide line, it can be a bit fiddly but have a go, good luck.
It's great to secure whatever you need to, to a bar or ring. The great thing with this knot is it tells you how to tie it in the name.