A Map (star chart) can be purchased from almost any outfitter from all governments. It will provide knowledge of nearby star systems to your hyperdrive navicomputer's galaxy map. The number of systems the map reveals depends where you buy it. For example, buying a map in Sol will only reveal systems 1 hyperjump in range, whereas buying a map in Auroran space will usually reveal 2 and sometimes up to 4 hyperjumps away from where you purchase the map.
This will only cost 1,000 cr per map and is extremely useful for travelers, as the maps add a variety of information about each included system, such as ports, hypergates, services, and traded commodities. Note that outfitters will happily sell you duplicate maps, so check your galaxy map (M key) before buying one to make sure you need it.