This can be done through hardware and software either ways but the important thing is the computers should be connected to each other via LAN or any Network connector.
1. KVM (Keyboard, Video, Mouse) switch, its hardware or say a cable in specific which will be a short one for keyboard, video and mouse. These are actually commonly used in Datacenters where lot of servers are placed in a single rack with a single keyboard, monitor and mouse. It will let you share a single mouse, keyboard and monitor across two or multiple computers. There is also KM switch cables using which you will be able to share a single keyboard and mouse with two computers that have two separate monitors. The best thing about using these hardware cables is they give really fast connections which makes it worth to go and makes the work more efficient. One of the main advantage of using KVM switch is that it saves space which would have been occupied if multiple keyboards, mouse are used.
2. If you don’t want to add any hardware cables there are a few software’s too which we can try, First thing to try out is Input Director, which is a Windows-only utility that’s easy to install and is totally free for non-commercial use. At first, you need to install this Input Director program on all your Computers. The computer that is physically connected by keyboard and mouse becomes the Master computer whereas the other systems will be Slave computers. Just make sure you never shut down the Master computer without turning off the Slave computers first because by doing that you will lose access to the keyboard and mouse which are physically attached to the master computer. There`s another program called Synergy , this one is a bit harder to setup than Input Director , but it’s free and a open-source thing which supports Microsoft windows, MAC OS and Linux. Both these programs are small ones which won’t eat up much resource your computers. On using both the software’s you don’t need to press any switches or buttons which was there in the case of KVM switches. Simply just move your cursor to drag drop or copy paste across your multiple computers in a easy manner.
People who don’t mind spending for a peaceful computing will love to go for the hardware way and the Users who don’t like to spend money and want a clean desk without messing with cables will go the software way. Happy Computing.