The remote API is part of the V-REP API framework.
V-REP offers a remote API allowing to control a simulation (or the simulator itself) from an external application or a remote hardware (e.g. real robot, remote computer, etc.). The V-REP remote API is composed by approximately one hundred specific functions and one generic function, that can be called from a C/C++ application, a Python script, a Java application, a Matlab/Octave program, an Urbi script, or a Lua script. The remote API functions are interacting with V-REP via socket communication in a way that reduces lag and network load to a great extent. All this happens in a hidden fashion to the user. The remote API can let one or several external applications interact with V-REP in a synchronous* or asynchronous* way (asynchronous by default), and even remote control of the simulator is supported (e.g. remotely loading a scene, starting, pausing or stopping a simulation for instance).
The word Synchronous is used in the sense that each simulation pass runs synchronously with the remote API application (i.e. the simulator will wait for a trigger signal from a client to start next simulation pass at a time t+dt). This is different from synchronous/asynchronous in the sense of blocking/non-blocking operation. The remote API also supports blocking and non-blocking operations.
The remote API functionality comes in 2 separate entities, that are interacting via socket communication: