A virtual proxy configuration is a set of modules mapped to a prefix. There can be several virtual proxy configurations for a single proxy.
The prefix is the part of the proxy URI before Sense or QMC (that is, /qps/{virtual proxy prefix}/Sense , if /qps/ is the base URI for the proxy).
The default prefix is an empty string, which means that the URI is /qps/Sense.
This allows different modules based on the URI to be used to access Qlik Sense or the Qlik Management Console (QMC).