A more thorough explanation:

A motion to strike is a request made to a judge to remove a part of a party's pleading or a piece of evidence from the record.

During the pleading stage, a motion to strike can be made by a party or raised by the court. This can be done using a tool such as Rule 12(f) of the Federal Rules of Civil Procedure or a state equivalent. Rule 12(f) allows a part of a pleading to be removed if it is redundant, immaterial, impertinent, or scandalous.

If a party includes irrelevant or scandalous information in their pleading, the opposing party can make a motion to strike that part of the pleading from the record.

At the trial stage, a party may make a motion to strike to remove evidence from the court record. This is usually done to remove part of a witness's testimony, with the jury instructed to disregard the evidence. A judge can either sustain or overrule the objection raised by the party.

If a witness provides testimony that is irrelevant or prejudicial, a party can make a motion to strike that part of the testimony from the record.

It is important to note that a motion to strike must be made in a timely manner, or else a party may waive the opportunity to raise it later.