Internal links work for linking to other wikis, and bypasses the need to paste in URLs (which tend to be both long and cryptic and make source text harder to read). This also avoids the appearance of the external link arrow ().
The long form does not work within the same project. The shortcut works everywhere.
Links to foreign-language Wikiprojects can be made by prefixing the language code: [[:de:s:]] will link to the German-language Wikisource, [[:fr:wikt:]] to the French-language Wiktionary, etc. You can use piped links ( "|" ) to avoid seeing the colons in the link.
