The US Season 1 DVD release from 2002 (Region 1) is the only one to include English subtitles, also as closed captions for the hearing impaired. This set has Spanish subtitles as well. The UK Season 1-7 DVD set (Region 2) and their Australian versions (Region 4) have no subtitles at all. The French DVDs feature both the original English and French audio, but only French subtitles for the episodes' original English language tracks, and also for the bonus features. The German DVD sets (with English and German audio tracks) have only German subtitles for the bonus features, not for the episodes. The American video-on-demand releases by Netflix and Amazon Prime have English closed captions.
Fan-made subtitle files in all kinds of languages and of varying quality, which you can link to some media player applications, can be found on sites like