Contexts are an advanced feature used to:
Most biometric applications are interactive and don't execute more than one biometric operation at a time, using just the default context. But, for example, to perform two fingerprint identifications simultaneously on a multithreaded server, each identification must be executed on its own context. Two operations must not be called simultaneously in the same context because they are not guaranteed to be thread-safe. Creating a new context for each operation that will be executed simultaneously guarantees the thread safety.
Furthermore, each context has its own matching parameters, making it possible to create different identification or verification environments. For example, in a two-level security biometric application, instead of tightening or lowering the matching parameters depending on the security level before performing a matching, two contexts, each one with the appropriate matching parameters, may be created; any fingerprint matching is then performed in a context corresponding to the right security level.