Here are some common reasons why cats have their tails raised:

Alert or excited: When a cat feels alert, excited or When curious, they may raise their tails. This may be a reaction to new objects, sounds or smells in the environment.

Confidence and Display: Sometimes, cats will raise their tails to show confidence or dominance. This may be when interacting with other cats or animals, or when they feel they are in a dominant position.

Friendliness or closeness: When some cats interact with humans or other familiar animals, they will raise their tails to express friendly and close intentions.

Uneasy or Nervous: In some situations, a cat with a raised tail may indicate uneasiness, nervousness, or uncertainty. This may be a reaction to an unfamiliar environment or potential threat.