As explained earlier, all Visual Basic applications before the release of VB 5 have been single-threaded applications. Most Visual Basic applications built using VB 5 will continue to be single-threaded applications. This is because the only Visual Basic applications that can be multi-threaded have to meet certain criteria - mainly that the Visual Basic application or DLL not require any user interaction. Threading in Visual Basic applications and DLLs is not quite your normal form of multi-threading; there are certain characteristics that set threads in Visual Basic apart from other programming languages that support threads.