Caveats are notices from parties who are not owners of lands that they are claiming some right or interest in the lands. Usually this claim results from some agreement entered into between the owner of the lands and the person who filed the caveat.
For example, many people give Manitoba Hydro the right to run power lines across their lands. Manitoba Hydro will register a caveat to let anyone searching the title know of their agreement with the owner of the lands. This is particularly useful for providing information to people looking to purchase lands.