When we say about Computer, it includes Hardware and Software. The physical part is called Hardware and the internal programs which runs the application is termed as Software. The performance of the Software is depended on the powerful Hardware you are using to support it.
The figure above shows the Computer Hardware which includes RAM, Data Storage which includes Hard Disk and other storage devices, CPU(Central Processing Unit), I/O(Input and Output).
RAM: its the temporary storage which helps to keep the software running in your operating system. Most of the applications are dependent on various other small piece of software, those various small patches are loaded in the virtual memory of the RAM. The maximum RAM you use, the maximum performance you will get since it increases the virtual space to run the applications.
Data Storage: this can be Hard Disk where all the files are saved including Operating System. External Hard Disk also includes data storage.
CPU: Central Processing Unit is a logical chip on which all the transaction executes and results are saved in Binary format on hard disk.
I/O device: Input devices take input to the RAM and CPU with the help of Input devices like Keyboard and Mouse. Output devices shows the output results on the monitor, printers or saves the output in hard disk.