Abarrier along the open sides of stairways and platforms that prevent falling

Explanation:

A barrier present at the open sides of stair case and platforms that prevent falling is known as a banister.

This banister is very helpful for old people and children as they need a support to move upwards whether it is a stairways or a platform.

Also, a banister is not used by any particular age group. It is for the people as a support to prevent them from falling.