A technology that has become out of date, unused or not popular. If something is borged it may become obsolete. Another reason things become obsolete is that a new technology, such as an invention, with much better functions and features than before, replaces what was once used. Sometimes obsolete items make it into the Halls Of The Dead.
Something may be old and still used as in legacy items. Items that become obsolete can still be used by a Hacker-Types, hardcore and other old school enthusiasts. Software updates make previous versions obsolete and Ultra Wideband promises to make slower communications outdated.