Procrastination refers to replacing important tasks with less important ones and putting off tasks to a later time. It can occur due to the pleasure principle of avoiding negative emotions from stressful tasks. While some anxiety from tasks can motivate early starting, impulsiveness can cause delaying if impulsive. For a behavior to be considered procrastination, it must be counterproductive, needless, and delaying. Chronic procrastination can result in stress, guilt, loss of productivity and undermine functioning, and may be a sign of an underlying psychological issue.

1. In psychology, procrastination refers to the act of
replacing high-priority actions with tasks of lower
priority, or doing something from which one derives
enjoyment, and thus putting off important tasks to a
later time.
Taken from Wikipedia, the free encyclopedia
http://en.wikipedia.org/wiki/Procrastination
In accordance with Freud, the Pleasure principle may
be responsible for procrastination; humans do not
prefer negative emotions, and handing off a stressful task until a further date is
enjoyable. The concept that humans work best under pressure provides additional
enjoyment and motivation to postponing a task.
Some psychologists cite such behavior as a mechanism for coping with the anxiety
associated with starting or completing any task or decision.[2] Other psychologists
indicate that anxiety is just as likely to get people to start working early as late and the
focus should be impulsiveness. That is, anxiety will cause people to delay only if they
are impulsive.
Schraw, Wadkins, and Olafson have proposed three
criteria for a behavior to be classified as procrastination: it
must be counterproductive, needless, and delaying.
Similarly, steel (2007) reviews all previous attempts to
define procrastination, indicating it is "to voluntarily delay
an intended course of action despite expecting to be worse
off for the delay."
Procrastination may result in stress, a sense of guilt and crisis, severe loss of personal
productivity, as well as social disapproval for not meeting responsibilities or
commitments. These feelings combined may promote further procrastination. While it is
regarded as normal for people to procrastinate to some degree, it becomes a problem
when it impedes normal functioning. Chronic procrastination may be a sign of an
underlying psychological disorder. Such procrastinators may have difficulty seeking
support due to social stigma and the belief that task-aversion is caused by laziness, low
willpower or low ambition.