Knots and the use of rope can be extremely important for an enjoyable and safe outdoor experience. From simple activities such as securing a tent to more extreme activities such as abseiling, the right knot can make a big difference.
The most important quality of an effective knot is that it is fit for purpose. Some simple knots can be ideal for simply tying down pieces of equipment but do not have the strength or security for more extreme activities such as winching people out of ravines. Having a knowledge of a range of knots will help to understand the right knot for the right purpose. More information on different knots can be found here.
Knots should also be able to be quickly made and easily undone. Like any other skill, knot tying should be practiced regularly to ensure that when the need arises, especially under pressure, that the right knot is tied and that it is done properly. Being able to undo the knot easily will also allow the rope to be used again and again, ensuring that a safe and enjoyable experience can be had.
Finally, understanding the security of different knots and ensuring that an appropriate knot is made is important. For example, figure of eight knots can maintain about 80% of the strength of the rope, whereas a bowline knot will maintain only 60%. Again, choosing the right knot for the right purpose can make a big difference. For those interested, an in depth article on the strength of different types of knots can be found here.