There are several ways to start a new page. These can vary, based on the type of page started, as well as the wiki and the namespace it is in.
From the search box
If you search for a page that doesn't exist (using the search box and “🔍” button at the upper right of the page), then the following line will appear:
Create the page "[Proposed Title]" on this wiki!
It will be above any search results should any appear. Simply click on the link to open the new page for editing.
Following a link to a page that doesn't exist will open it for editing. On some wikis, you might not be able to create a new page unless you are logged in.
New page links typically look different from links to existing pages. Depending on settings, a different color or a question mark is used. (Sometimes links to new pages are called "red links", the display option of one of the settings). Links to non-existent pages are created with [[New page name]] from the wiki editor. (In this case, the empty page "New page name" would be created).
Links to non-existing pages are common. They are typically created in preparation for creating the page and/or to encourage other people to do so. Links are not only convenient for navigation, but also make people aware of the new page (those who read a related page and also those who watch the related page). New page links are not truly broken as long as the name correctly identifies the intended content. (A new page link with a "wrong" or misspelled name, or that duplicates content found under another name is "broken", but in a different sense.)
Of course, you can also create the link yourself, in a related page, index page or your user page. However, it may be better to wait to create links until after creating the new page, especially if the new link replaces one to an existing page. In this case, create the link but press Preview, instead of Save. From preview area, clicking the new link will create the new page (without updating the referring page).
Using the URL bar
Using the browser address bar to enter a URL (web address) to a new page is another way to start the new page process. Easier still is editing the page name part of a URL for an existing page. Using the URL for the new page displays the default 'no article' message. The default page has the usual Edit this page link, which can be used to begin adding content.
From the Community portal
The Community portal on all wikis has a "Start a new article" bullet point by default. Typing in the name of the page and clicking the now blue 'Create page' button will redirect to the default page with the usual Edit this page link, which can be used to begin adding content.
New pages and blank pages
A new page is distinguishable from a blank page: the latter has a page history. Creating a new page is similar to editing a blank page, but links to blank pages are not red, unlike links to new pages.
Categories and category pages are technically separate, and a category can exist without a page. When you open a category page that doesn't exist, you may see that that pages are already in the associated category. The main use of category pages is to put categories within more general categories, as categorizing the category page will categorize the category too. This allows a wiki community to create a hierarchy of categories. Category pages can also be utilized to provide further information on the type of articles contained in the category.
Image files and file pages are also technically separate, but typically a link to a file page will not be red unless the image is missing. File pages are useful for categorizing images, showing license information, and providing a description of the image.