Claims

A set of numbered statements contained in a patent specification that set out ​the scope of protection that is provided by a patent (or sought by a patent application). 

There are two types of claims, independent claims and dependent claims.  Independent claims set out the broadest scope of protection.  Dependent claims refer to the independent claims and specify additional features (or "limitations") that further narrow the scope of protection. 

The claims are arguably the most important part of a patent specification and are the main focus during examination when a patent office is deciding whether to grant a patent.  They are also used by a court to assess whether a third party is infringing a patent.  Identifying and defining an optimal scope of protection is therefore a key consideration when drafting a patent specification - too broad and a patent application may fail to pass the key patentability requirements for novelty and inventive step - too narrow and the patent application may be easy for a third party to avoid infringing any resulting patent.