If the only tool you have is a hammer, you tend to see every problem as a nail.

– Abraham Maslow

Intellectual Property Offices/Agencies
United States Patent and Trademark Office (USPTO)
World Intellectual Property Organization (WIPO)
European Patent Office (EPO)
Canadian Intellectual Property Office (CIPO)

Patent Searching
USPTO – Search for Patents
WIPO – PATENTSCOPE – search published international patent (PCT) applications
Espacenet – worldwide patent search
Google Patent Search
Google Advanced Patent Search

Public File Inspection
USPTO Patent Application Information Retrieval (PAIR)
European Patent Register

Download Patents And Published Patent Applications In Pdf
pat2pdf.org – download US patents and published applications
Patent Retriever – download US and European patents and published applications, as well as published international (PCT) applications