A motion is a written request made by a party in a legal proceeding to the court. It's a formal document that outlines and states the grounds for the request being made of the court. Motions are subject to a variety of technical requirements which vary between jurisdictions. The person submitting the motion is called the movant. There are lots of different types of motions but they generally can be categorized as being one of two types—hearing or non-hearing. As the names of the categories suggest, the difference lies in whether the ruling is produced pursuant to a hearing or not.
Whether a motion is a hearing or non-hearing motion, it will generally include various documents including the moving papers or written memoranda and supporting evidence such as affidavits and exhibits. Hearing motions have the added step of having the attorneys appear before the court to orally argue for their respective positions on the motion.
Whether the motion is a hearing or non-hearing motion, the court will answer the motion by making a ruling. That ruling is generally documented in a minute order or written order produced by either the court clerk or one of the attorneys.
While there are many different types of motions, a motion to dismiss and a motion for summary judgment are two common, or well-known types. A motion to dismiss is made when a party wants some evidence excluded from the trial. A for summary judgment is a request for the court to make a final ruling without actually trying the issue, or more precisely, the cause of action, in court. If the material facts are not disputed, that is, if the only issue is a question of law, not a question of fact, then the court can make it's decision without bringing the issue through the formality of a trial. Trials are held to address issues of fact. Whether the defendant ran a red light or not is a question of fact.
Many motions are commonly made in a given trial. They are not only helpful in reducing trials to the core dispute or disputes but they can also be a helpful tactic in getting evidence for oneself or precluding evidence for one's opponent.