A party enters an appearance when they show up to court in response to a service of process. Appearance isn’t only a reference to physical presence in court when required, but also to procedural compliance (e.g., filing an answer, participating in discovery). Typically, making an appearance means that you consent to the court’s exercise of personal jurisdiction over you, and you therefore waive your right to challenge it later. This type of appearance is known as a general appearance.
If a party does not believe the court can exercise personal jurisdiction over them but does not want to risk the possibility of a default judgment nor the risk of losing an otherwise valid lack of personal jurisdiction defense, they can enter a special appearance for the exclusive purpose of determining jurisdiction. In federal court, there is no longer a distinction between a general or special appearance, however, a FRCP 12(b)2 motion allows a party to accomplish the same thing a special appearance would.
A party can make an appearance either in person or virtually, although the availability of these depends on the specific court and specific issue.
[Last updated in June of 2022 by the Wex Definitions Team]