Unlike traditional encyclopedias such as Encyclopædia Britannica, no
article in Wikipedia undergoes formal peer-review process and changes
to articles are made available immediately. No article is owned by its
creator or any other editor, or is vetted by any recognized authority.
Except for a few vandalism-prone pages that can be edited only by estab
lished users, or in extreme cases only by administrators, every
article may be edited anonymously or with a user account, while only
registered users may create a new article (only in English edition).
Consequently, Wikipedia "makes no guarantee of validity" of its
content. Being a general reference work, Wikipedia also contains
materials that some people, including Wikipedia editors,may find
objectionable, offensive, or pornographic. For instance, in 2008,
Wikipedia rejected an online petition against the inclusion of
Muhammad's depictions in its English edition, citing this policy. The
presence of politically sensitive materials in Wikipedia had also led
the People's Republic of China to block access to parts of the site.