The original connection not found on modern machines. You can still connect to this using adaptors from DVI, HDMI and display port but it gives the fuzziest picture of all connectors to try to use one of the others if possible.
A digital only version of a DVI socket – will connect to other DVI connectors but cannot use a DVI-VGA adaptor.
This version of DVI has 4 extra holes over the horizontal line which can provide an analogue signal to a screen – so you can add a converter to change it to VGA if needed.
Now very common, and used to connect cameras to TVs etc this can also be used for computer screens and is practically the same as DVI.
Modern connection which can handle 4K @ 60P. You can buy adaptors to covert this to any of the other connections, including VGA.