There are two reasons. You delegate to make your company more profitable. You delegate to make your life easier. Sounds good, but it's easy to dump and think you're delegating.
You can only delegate effectively if the person you are delegating to has the ability and willingness to do what you want. Ability includes knowledge and skill, but it also includes resources and organizational support.
Willingness includes motivation and confidence. Motivation is the behavior of voluntarily and enthusiastically pitching in. Motivation is global. The folks who are motivated are probably motivated about everything all the time. Sometimes a motivated person may not pitch in on a specific task because he or she lacks the confidence that they can do it well.
Here are some tips about delegating.
You delegate specific tasks or clusters of work. A person can have the ability to handle some things but not others.
You must make sure that your wishes are understood. According to my research, bosses almost uniformly give themselves better marks on this than they get from their subordinates.
In my research, I've found that bosses have a tendency to move from directing behavior to delegation without passing through a stage of "supervised delegation." That's usually a bad idea. Folks develop the ability and confidence necessary to handle important work over time. Bosses develop the confidence to let them, and develop their own skills at delegating.
Delegating means allowing someone who works for you to make decisions about when and how work will be done. But how you do that will vary from individual to individual based on their own personal style.