Welcome to my userpage. This page isn't really all that interesting (but it's at least less embarassing than the last edit), nor does it have much of a point since I haven't done much serious editing on here in a long, long while, but you can browse here if you're so inclined. (to find a giant page full of userboxes, go here)
Wikipedia has a sister project that presents hundreds of thousands of word definitions. It's called Wiktionary. Let's say you are writing a sentence and you want to create a link to the definition of a word, the understanding of which is crucial to understanding that article. But in this hypothetical situation, you don't want to link to the Wikipedia page for that word because doing so would be overkill. So, using our Source Editor, here's how you would provide a link to the definition of "understanding" on Wiktionary:
both [[wiktionary:understanding|]] and [[wikt:understanding|]] will display like this: