A map is a depiction of an area of land or sea, showing the shape and position of natural and artificial geographical features as well as political borders. Maps exist in both physical and digital formats. Geographical data, often called geodata, are attribute data linked to physical locations. Geodata can be presented in the form of maps, either as a matrix or as points, lines and polygons.
Maps and geographical data, in any form, are subjected to copyright law. Unless it is clearly stated that the map or geodata are not copyrighted, you can be sure that they are. Many online map services contain maps and geodata from several different sources. The base map, which forms the background setting, and the geodata in a map service usually come from different creators. If you want to use a map consisting of several map layers, the creators of all visible maps and geodata need to be asked for permission and credited. Make sure that the permissions are in writing and that you save them.
There is usually no peer-reviewing of maps and geodata, unless they are part of a scientific publication. When there is no formal quality control, you will need to determine for yourself if the information is credible and relevant. A first step is to identify the provider of the source, to establish whether there is a recognized authority or organization behind the map or the geodata. Examples of trusted geodata sources are government agencies such as the Swedish Surveying and Cadastral Agency (Lantmäteriet) and Sweden Geological Survey (Sveriges geologiska undersökning, SGU). You can find more advice on what to consider when evaluating a source in the section Evaluating informal sources.