The IBM Patent Search Site is http://www.delphion.com/. In the IBM Patent search site it uses its own relational database technology to offer free searchable access to patents from 1971. Patents in IBM Patent Search can be searched by number, simple text search, Boolean text search in one or two patent fields or advanced text search in any searchable field. Searchers have mentioned that the IBM Patent Search server can be slow and that occasionally patents or pages are missing from the database.

The first series of steps are to discover the "field of IBM patent search" which identifies the proper classifications to locate a particular patent. This consists of four steps:

1. Identify the parts of an invention. Its component parts classify an invention
2. Search the Index to the U.S. Patent Classification. Look up the terms in IBM Patent Search that most closely describe the invention or process's function, effect, end product, structure or use. Write down all relevant class and subclass numbers.
3. Use the Manual of Classification. Look up the classes and subclasses in IBM Patent Search you retrieved in the previous step. Revise your strategy as needed by eliminating any false leads.
4. Consult the Patent Classification Definitions http://www.uspto.gov/web/offices/ac/ido/oeip/taf/def/index.htm. Read the definitions to establish the scope of classes and subclasses.
   The next series of steps of IBM Patent Search is the "Prior Art" which identifies patents within the designated classifications:
5. Review the Subclass Listing. Retrieve a list of all patent numbers granted for every class and subclass to be searched.
6. Locate patents by number e.g., in the Official Gazette. Use the OG to look at a claim of a patent and eliminate those unrelated to the invention.
7. Obtain complete patent document. Complete patents are available, in print, microform, CD-ROM and online formats. It should be emphasized that currently not all years of all patents are available free of charge in IBM Patent Search online. Complete patents are available from Patent and Trademark Depository Libraries (PTDLs) http://www.uspto.gov/web/offices/ac/ido/ptdl/ptdlib_1.html.

Patents can also be used as a ready reference source for IBM Patent Search as well as the result of a literature or state of the art search. With less demand for subject searching than for search by inventor, assignee or patent number, using one of the web-based patent search sites is often ideal. Patent-related sites could contain general patent information, lists of classes and subclasses, abstracts and full-text patents. Depending on the information need of the client, the abstract or "front page" information (patent number, title, date, inventor, assignee application number, application date, abstract, figures, number of claims, and references cited) of the patent may suffice.