Usually, it’s in the form of a claim against that property by another person other than the property owner.
Generally, liens can be divided into voluntary and involuntary liens. A voluntary lien is one that you agree with.
Deed restrictions are most common when a large piece of land has been subdivided into smaller properties, such as in the creation of a new neighborhood.
A mortgage is an encumbrance because it’s an agreement between you and a mortgage provider that restricts you from selling the property unless you pay off what you owe.
The most common form of encroachment as an encumbrance is when a neighbor mistakenly places an improvement such as a shed or a fence beyond their property line.