When you tie your shoe laces, you're probably using a square knot [1] but with double slip. If your shoe laces often open while walking, you might be doing it wrong (granny or thief knot).
If you want to learn just one new, very convenient knot, which can be used in many situations, I recommend the Bowline [2].
If you want to learn just one new, very convenient knot, which can be used in many situations, I recommend the Bowline [2].
[1] https://www.animatedknots.com/square-knot
[2] https://www.animatedknots.com/bowline-knot