Page Contents
This page:
lists major IP web portals a researcher can access to search for patents and applications. Some allow patent family searches.
Patent searching, however, is a very technical endeavor. You can find patent information if you have a patent or application number. However, searching by keywords, inventor name, etc., may not give satisfactory results. In that case IPC patent "classes" and other specialized knowledge has to be used.
A Common Citation Document (CCD) database search system is being implemented. Those site pages are not listed here.
Google Patent Search
A Google Patents search will return US patents since 1790 and EPO and WIPO granted patents and published patent applications from 1978 to date.
A live search box is provided below with a default search term you can run or replace with your desired query. If you do not know the exact patent/application number involved, using the advanced patent search page is recommended.
WIPO Searches
The database provides access to international Patent Cooperation Treaty (PCT) applications in full text format..., as well as to patent documents of participating National and Regional Patent Offices. The information may be searched by entering keywords, names of applicants, international patent classification and many other search criteria...
PatentScope Advanced Search page.
Searching International and National Patent Collections:
PATENTSCOPE's "External Databases" lists links to the national patent search pages for most major countries.
European Patent Office (EPO)
The EPO searching pages are composed of:
Espacenet, the EPO's comprehensive patent searching tool.
That search utility is preceded by a "Searching for Patents" landing page that serves as a gateway to Espacenet, a "Patent Information Essentials" page which contans short overviews of patents and patent classification and links for an interactive "tour".
Finally, information on EPO "Patent Families" is available.
"Landscape Reports"
In addition to patent "families" comprised of related patents, various organizations have compiled "Patent Landscape Reports" covering a technology sector or type of invention. These are broader in scope than a patent family search, and sometimes provide analysis of geographical and industry trends.
WIPO has prepared several of these reports, and posts those as well as a link to numerous others prepared by various organizations at this Patent Landscape Reports page.
from the USPTO
The USPTO now provides coverage from SIPO, mainland China's State Intellectual Property Office. USPTO intends to add coverage for other countries in the future.
► Global Patents Search Network (GPSN) Search Chinese full-text patent documents in the English or Chinese language, including: published applications, granted patents and utility models from 1985 to 2012.
The USPTO's pages also contain search help overviews, and detailed tips and this Search International Patent Offices handy list of links to search pages of major IP offices.
Westlaw
Westlaw patent search information can be reached from either the "Intellectual Property" or the "International Materials" links on the third column of the search categories at the home page (to the right of the two columns used in an "All Content" search).
Since patents aren't listed as a category type, just enter the term "patent" in the search box. Chief among the many sources returned are the
"PCT Patent Applications" and
"Derwent World Patents Index." College of law log in is required. 
Lexis.com
Lexis.com coverage lets you search foreign & WIPO patent and trademark filings. The best method is to search by country in Foreign Laws & Legal Sources. That database is reached from the LexisAdvance Research Home Page > Research: "v" > Lexis.com > Find Laws by Country or Region > Foreign Laws and Legal Resources.
You can also use the "Add/Edit Subtabs" icon to add "Patents" as a tab. That tab will let you check off for filtering on European, PCT and UK patents.