Free knowledge is the philosophy that public knowledge should be freely available to anyone, in the interest of education, learning and research.
"Public knowledge" is knowledge whose publication does not infringe any legal rights, such as intellectual property rights, copyrights, commercial rights or personality rights. Such knowledge is thought to "belong to everyone", and everyone should be permitted access to it. Advocates of free knowledge are generally opposed to censorship; however for practical reasons most accept certain censorship which is prescribed by national or international law.
Free knowledge is also known as libre knowledge. There is a certain difference between the adjectives "free" and "libre": libre explicitly refers to free as in "free speech", not to gratis as in "free beer". In German, a similar concept to free/libre knowledge is called Wissensallmende.
Free knowledge on the InternetEdit
The philosophy of free knowledge boosted Internet knowledge databases such as Wikipedia and thousands of other wikis. The spirit of free knowledge is so popular nowadays that hundreds of thousands of hobby authors worldwide spend countless hours of their leisure time to contribute knowledge to such databases for no payment, just because they want this knowledge to be available to all mankind.
In wikis, knowledge is not static but is dynamically developed and advanced through a collaborative process. Usually, wiki content is under a free license such as the GFDL, and access to wikis is unrestricted and requires neither membership nor age verification. So the content is not only libre but free in all senses of the word.