Vst plugins are software instruments & effects that can be used in digital audio workstations (DAWs). They are a standard format that allows developers to create and distribute audio plugins that can be used in a variety of DAWs.
Installing audio plugins is a relatively simple process.
In this video I walk you through the process of installing these great tools in windows (is very similar on Mac), also talk about vst2, vst3 & some troubleshooting.