A NAS drive or Network Attached Storage is quite simply what it says on the tin. It is a storage device that is connected to the network and can be accessed by all the devices on that network. This central point of storage provides many benefits. Generally, if you the buy the write NAS it will have a decent amount of storage in it, Usually several TB.
A NAS drive can be used in one of two ways, it can either be used to do backups of devices on the network, which makes sharing data between the devices a little awkward. Or it can be used as a central storage and if you have one with enough storage you can do device backups at the same time. If you use the NAS as a central storage then you will be limited only by the size of the NAS, and your network speeds, instead of the size of the device you are using.
In a way, a NAS is a in-house cloud. It allows you a place to store your files that you and others are working on and gives easy accessibility to it all. Also, a lot of NAS’s will allow external access through a web page so when you are out of the house or office you can access the files just like you would with any other cloud service, just without the monthly bill.