The thing that makes this a "Wiki", as opposed to just a collection of editable pages, is the ability to create "links" between pages.
In the "classic" formatting, a link is created by using a "WikiWord" by placing two or more initially capitalised words together, CamelCase-style (e.g., HomePage). If the page exists, you'll see a link to it; if it doesn't exist yet, you'll see the name in red (like this), which you can then click to create the page. You can get the same effect by putting the WikiWord-to-be between {{curly brackets}}; and if the WikiWord is just a single word, curly brackets are the only way to do it. It is recommended to use CamelCase when possible, and curly brackets only for single-word WikiWords.
WikiWords partially match the URL (page address in browser) of the page they link to. For example, for https://tvtropes.org/pmwiki/pmwiki.php/NamespaceGoesHere/TitleGoesHere
, "NamespaceGoesHere" is the Namespace, "TitleGoesHere" is the page's name, and "NamespaceGoesHere/TitleGoesHere" make up the WikiWord for Title Goes Here. Placing "Film/TheEmpireStrikesBack" on a page will turn it into The Empire Strikes Back, while for Futurama, curly brackets must be used to make the correct link: either "{{WesternAnimation/Futurama}}" or "WesternAnimation/{{Futurama}}". Using a period instead of a slash in the wikiword will make the namespace visible: "NamespaceGoesHere.TitleGoesHere" shows up as NamespaceGoesHere.Title Goes Here.
WikiWords without a namespace default to the Main/ namespace, which is where the Tropes are. They don't require being specified in the WikiWord, so "Main/" should be omitted unless absolutely necessary. "BigBad" will link to Big Bad and "{{Filler}}" will link to Filler.
Note that the capitalization is sort of ignored on the linked page: Home Page and Ho Mepage link to the same place. This does not make the latter any less wrong, and has a risk of creating a page with a capitalization error in the URL.
In addition, punctuation doesn't work with WikiWords. It appears automatically if the page has a title with punctuation set up by a mod. See How to Make a Custom Title to request punctuation and nonstandard characters for a title.
See also Text-Formatting Rules for specific details about the format and other ways of linking. Also check "Escape Sequence" there for what to do if you need to use CamelCase without creating a link.
