Africa Growth Pilot/Online self-paced course/Module 4/Wikipedia is a tertiary source
Wikipedia strives to publish verifiable information about notable subjects in a neutral voice. So we've covered the neutral voice, the Verifiability we're covering today, and Notability in the next module.
One key principle in verifiability is that Wikipedia's content is determined by previously published information. No information on Wikipedia should be appearing publicly for the first time in the Wikipedia article. If you have just made an amazing discovery in physics, don't write about it on Wikipedia; Go tell your scientist friends, publish a peer-reviewed article, a scientific article, about it, and then, eventually, Wikipedia would also report about your amazing physics discovery.
Wikipedia should not be the first and only source for any piece of information. This principle is called "No Original Research". This is important to keep in mind. It's not enough that you know something is true. You have to be able to show where it is already stated, before the encyclopedia can repeat it. The encyclopedia is what's called a tertiary information source. Tertiary is just a fancy word from the number three. It's like a third-order information source. It's not a primary source, like a text written by an author or by an eyewitness, or issued by an institution. It's not a secondary source in the sense that it's not an academic work or a reference work that is analyzing or criticizing or commenting on a primary source. It is a tertiary source in that it seeks to offer summary opinions, aggregate surveys of what the secondary sources are saying, of what other people who have analyzed and critiqued and sifted through evidence have said. The encyclopedia is a further distillation of knowledge from the secondary sources. It is a tertiary source.