Because the claims of each patent application define its invention(s), are searched and examined before a patent can issue, and ultimately give rise to the particular legal rights held by the owner of the patent, the claims are a very important part of each patent application.

Assuming that the results of the Patentability Search were hopeful, a skilled patent attorney can typically draft claims that have a reasonable likelihood of receiving a favorable reaction from the patent examiner, and will be issued in a patent.

If special care is taken in the search and drafting process, these issued claims have a good chance of being upheld if challenged via litigation. Because poorly-drafted claims can be refused by the examiner as unpatentable, or can result in an issued patent being held invalid, the drafting of the claims should be left to a skilled patent attorney.

Such a skilled patent attorney will typically draft claims of several different types, and of varying scope. Typically, claims for devices, systems, compositions, or methods are drafted. In certain technology areas, additional claim types are sometimes presented. For example, in the software realm, claims have been drafted for unique data structures, user interfaces, and waveforms. For biotechnology, claims for vaccines, assays, and diagnostic kits are common.

Claims are classified as independent or dependent. Independent claims refer to no other claim. Dependent claims refer to another claim. Patent applications contain at least one independent claim, and typically 3 or more.

Often, the claims will contain what appears to be arcane language and a run-on structure, both of which are traditional.