Good question. Virtual Tabletop applications simulate a live game, as is normally played in roleplaying games, where you can upload a map, tokens representing player characters, non-player characters, monsters, trees, etc. And play online, however, the resolutions used by the varying VT apps vary. Roll20 is a very popular, largely free VT app, and it uses 70 dpi, on an area up to 72 x 72 inches. Other programs like Battle Grounds, Fantasy Grounds, Map Tools, can allow many dpi variances from 100 - 200 dpi. The larger the dpi, the longer it takes tokens and maps to download to other computers of other players to view on their screen, but of course higher res is better quality. Also, some people might use the tokens on maps they create using Xara, Photoshop or whichever graphics application they prefer to use, so offering 300 dpi tokens, allows users to create printable maps.