There are many types of threads, which are divided into several categories. The most common
of these are metric, inch (e.g. BSP or NPT) and special threads (for specific applications). However, the number of thread varieties is so large and dependent on specification, purpose and industry standards that it is difficult to list them all here.
Therefore, when selecting threaded fittings, it is worth paying attention to the thread type. It should be compatible with the rest of the system.