Character Encoding (Charset)
This is the term for code systems used to store and display text of various languages in electronic form. Common encoding systems that support Japanese are Japanese(EUC), Japanese(JIS), Japanese(Shift-JIS), Unicode(UTF-8). Of these Japanese(JIS) is probably the most common for use on web-pages.
Web servers should specify the correct charset when serving web-pages, or charset information can be given in the <meta> tag of pages. If your browser has the wrong encoding selected when viewing a page it may appear as mojibake.