In common usage, the phrases "anally retentive," "anal-retentive" or "anal" are used to describe a certain style of behavior, and it is implied that this is due to a person clenching their anal sphincter, causing retention of feces. This is not necessarily literally the case, nor usually even intended literally.
A person characterized as anal-retentive is perceived as worrying excessively about "passing feces": little details of fecal consistency, color and aroma or as otherwise being overly uptight or distressed over ordinarily normal evacuation.
Today, however, the term is often used of anybody seen as overly worried about small details and unable to adopt a philosophical attitude toward mistakes. This metaphorical usage has become so commonplace that the somewhat graphic literal meaning of the phrase is often overlooked by those using it.
Then the child typically moves on to the "anal stage" which is characterised by the child deriving pleasure from bowel movements. The child discovers the pleasure which comes from the exercise of power (in this instance the power to hold on or let go.)
After the anal stage the child's development will be able to move on to the "phallic stage" when the child's focus of attention will shift to the genital region. Freud believed that conflicts with parents and delays during toilet training can cause a person to become fixated on anal control, which later manifests itself as a compulsive concern with order, cleanliness and retention of assets.