A scrum consists of everyone everyone in a group standing in a circle and one by one answering 3 simple questions:
After a person answers those 3 questions (should only take around 30 seconds) the person will say "No Blockers" (even if the person listed blockers) to let the person to the right of them know it's their turn to speak. The scrum is always conducted in a counter-clockwise direction to symbolize an attempt to get back the time lost standing in the scrum.
After going around the circle, people can have aftertopics that can last longer. People who aren't concerned with any of the aftertopics can leave.
If anyone isn't answering the 3 questions properly, the scrum master needs to stop them and say "this should be an aftertopic".