Many of the pieces of Scrum are deceptively simple. In their simplicity, where many feel they have a clear understanding, the fact is that they really don't. As Ken Schwaber has a habit of saying, "Scrum is simple, but really hard." The daily scrum is a perfect example of this. Of all the events I have witnesses over the years, it is the Daily Scrum that is more often not just done wrong, but done completely wrong (in fact, there are more tips coming in the future about the Daily Scrum).
The Daily Scrum is about communication (not status reporting for the Scrum Master, as many teams believe). As a result of studies done many years ago that show that project success has as much, if not more, to do with communication amongst project team members as anything else (including team size).
The Daily Scrum is also about accountability. Did everyone do what they said they were going to do? If not, why not and what do we need to do as a team to get back on track? Daily Scrums keep the team accountable to one another and go along way toward eliminating unwanted surprises during the Sprint.
One of the best ways to make a Daily Scrum ineffective is to allow the event to be interrupted by conversations that are outside the scope of the questions being answered. For example, while answering the question, "What have I done since the last Daily Scrum to help my team achieve the Sprint Goal?" it would NOT be considered appropriate to begin discussing the all work that you did to diagnose and fix a problem. The reason this is true is because we're asking our developers to listen to one another and try to create, in their minds, a view of what everyone is doing and if what they hear might indicate a problem. Too much detail, and we quickly lose track of what everyone on the team is trying to communicate. Also, because our team is cross-functional, discussing a particular issue in depth is probably going to leave a few developers standing there wasting time.
While the Daily Scrum is a great time to raise issues, it is a lousy time to discuss them. Many Scrum Masters have what they call the "sixteenth-minute," a reference to the maximum 15-minute time box of a Daily Scrum. During the 16th minute, which can last fifteen or more as needed, the team discusses any issues raised during the Daily Scrum and decides what steps to take next.