Constipation is an acute or chronic condition in which bowel movements occur less often than usual or consist of hard, dry stools that are painful or difficult to pass.

Generally speaking, humans should have at least one bowel movement daily, in the AM shortly after arising.  Some humans have bowel movements within a short time frame from each meal.

For others, things do not work so smoothly.  Having bowel movements every 2 to 3 days is not normal. What is happening is the solid waste material is compacting and backing up just above the level of the anus, in the rectal and descending colon.  See picture above.

Solid food waste moves from your small intestine, into the ascending colon where you see the appendix.  Solid waste then moves up the ascending, across the transverse (part of colon going straight across the lower abdomen), and down the descending colon.  When solid waste moves into the rectum, it stimulates nerves that tell us it is time to head to the bathroom. Solid waste then leaves the body through the anal opening.

When this does not work so smoothly, meaning things get backed up, and constipation is the result.