In order to understand how spatial data on the web works, we first need to get a picture about the architecture of the web. The web resides on the Internet, where we have to deal with two kinds of software--servers and clients:
- Server: An application that listens to a port with a background process (daemon), and accepts requests from that port. It processes valid requests and serves data according to them.
- Client: An application responsible for sending valid requests to server side application(s) (for example, web browser-web server, SSH client-SSH server, QGIS-PostgreSQL). It also needs to be able to interpret the response sent back from the server.
If you are familiar with the client-server architecture, you can skip the following subsection.
