The file extension GPX identifies a GPS Exchange file, ie an exchange file for GPS data. Gpx files contain data in GPS Exchange format, which includes location data, routes and waypoints. The GPX format is based on the general XML standard and is an open and license-free format.
GPX files can be opened with many GPS data processing programs and any text editor or XML editor. As an XML-based format, GPX also allows the embedding of extensions. This is for example used by Garmin to store more data. However, these files can only be processed by Garmin products.
GPX is a widely used format, and with the versatility of GPS data, such as the interchange between mobile devices, route planning, 3D views for flight logs, marine navigation, and more, there is of course an unmanageable number of programs, the GPX format can handle. There is a fairly large overview http://www.Topografix.Com/gpx_resources.Asp on the page of the developer of the GPX format.
Most often resolving problems with opening GPX files is very simple. Just install an appropriate program that supports such files. All of the listed programs support GPX files, but may vary in offered function and purpose. Some programs may be capable only of viewing contents of GPX files or offer file conversion options, but may not be capable of editing such files.
It is possible that although a compatible program has been installed on user’s system, it is not used by the system to open it. This may happen because no default application was associated with this type of files. To associate GPX files with given application, select "Open with" from drop-down menu (accessed by right-clicking on the file). Then select from the list the program or application you want to be used to open this type of file. If the Google Earth applications is not on the list, select "Browse" option in order to manually locate the directory where Google Earth has been installed.
Sometimes problems with opening GPX files may not lie with the application itself, but can arise due to other causes, such as: