A more thorough explanation:

Definition:

1. The area located in front of or next to the bench that is separated from the witness stand and the jury box. During a trial, judges may ask attorneys to speak privately with them in this area so that the jury cannot hear what is being discussed.
2. To participate in a private discussion with another party during a trial.

Examples:

• During the trial, the judge asked the defense attorney to approach the sidebar to discuss a legal matter.
• The prosecutor and defense attorney had a sidebar conversation to negotiate a plea deal.

The first example illustrates the physical location of the sidebar in a courtroom and how it is used by judges to have private conversations with attorneys. The second example shows how attorneys can use the sidebar to have confidential discussions during a trial.