Geospatial resources are provided through open source and commercial channels meeting a wide variety of user requirements. A key difference between the two resource types is that payment is usually required to access commercial resources while open source resources are provided free to the community. Exceptions always exist, so look around and ask questions when needing access to specific geospatial data or tools.
The Geospatial Centroid works to maintain a software stack of various commercial and open source software, links to which you will find to the left. We are always interested in adding to the stack so if you would like to suggest something to add please do!