Virtual Memory And services provided by an operating system

In this post i want to share some information about Operating system .

VIRTUAL MEMORY :
Virtual memory is a memory management capability of an operating system that use hardware and software to allow a computer to compensate for physical memory storage by temporary transferring of data from ram to ROM(hard disk) .
It works when there is not enough space in ram to run a program .

EXAMPLE:
When a computer has 5 application open at same time ram wouldn't be enough to handle all of them so virtual memory help ram to handle all these .

Services Provided By An Operating System:

(1) Program development:
Operating system allow developers develop an error free program.

(2) Program execution:
Operating system helps to load and excute already installed programe:

(3) access to input and output devices:
different system may have different Input output devices at different address Needed different software To derived them .So operating system helps them to find address and work properly.

Source (i got this information from my teacher and written in my own words).

I hope you learn it.
Thanks for reading .