Hardware is the physical part of any technology. For Computers, there are several physical elements you would need. There are two requirements for any device. First is a power source often called a power supply. Second is where it is housed. In many cases, they are housed in a mini-tower or just a case that has many connections.
All parts connect to a Motherboard or Central point. Motherboards connect various components together inside such as:
RAM aka Memory
Outside the Motherboard, there are many external devices that can be connected to the Computer via either USB, network, or wireless technologies. Examples include:
Flash Drive or External Hard Drive