This essay is about the law of infobox inclusion, a ceteris paribus law regarding which articles on Wikipedia contain an infobox(s). The principle is stated as followed:

• Every article on Wikipedia that is not also a (may be eponymous) category contains an infobox or ought to contain an infobox for the sake of uniformity of the encyclopedia, all else being equal.

This is an essay. It contains the advice or opinions of one or more Wikipedia contributors. This page is not an encyclopedia article, nor is it one of Wikipedia's policies or guidelines, as it has not been thoroughly vetted by the community. Some essays represent widespread norms; others only represent minority viewpoints.

Shortcut WP:LII

This page in a nutshell: All else being equal, every article about an individual person, individual object, or individual entity will contain an infobox.

The principle essentially states that an article on Wikipedia would contain at least one infobox if its topic is a token (an individual person, object, or entity). Here are some examples:

• A specific individual (such as Yingluck Shinawatra)
• A specific place (such as Sacramento)
• A specific organization (such as Alibaba)
• A specific astronomical object (such as Saturn)
• A specific ship (such as the Yamato)

There are various exceptions to this principle/law, which is what are meant by the 'all else being equal' clause. A notable category of these exceptions is classical music composers, such as Edward Elgar. There are many reasons why an exception might occur, i.e. when an article about a token does not contain an infobox. Possible reasons include opposition by the local WikiProject (because infoboxes are purported to reduce an encyclopedia to a database or a PowerPoint presentation), and the article being still a stub. Attempts to break through this opposition led to the Infobox War that ended in 2013.

It is important to note that the converse of this law does not hold. In other words, it is false that if an article contains an infobox, then it is not also a category with articles in it. The obvious counterexample is the article New York City and its eponymous category.

• Wikipedia:Wikipedia Signpost/2013-10-02/Arbitration report
• Wikipedia:Disinfoboxes
• Wikipedia:Disinfoboxes: a refutation