Traditionally, air compressor hoses were connected to air tools using threaded fittings. These fittings have to be twisted on and off every time you need to change tools. While they work just fine to preserve the pressure needed for the tools to function, many people find them to be a hassle to use with most air compressor accessories.
Luckily, there are other fittings that work much better, including quick-connect couplers.
The video posted here has a lot of information about how these fittings work and where they can be used. Basically, any time you are working with multiple air tools in quick succession (like technicians working in an auto shop often need to) you will likely want to use a quick-connect coupler instead of a threaded fitting.
To use a quick-connect coupler, simply pull back on the outer ring of the coupler, slip the inner ring over the air compressor connection on the tool, and release the outer ring to create an air seal. There is typically no twisting required, and you don’t ever need to use another tool to connect air compressor accessories to the air compressor when using a quick-connect coupler.