Question

what are public interest pressure describe theirfunctioning

Answer 1

The public interest pressure groups which helps you better in understanding their objectives and functions. Public interests pressure groups also called promotions groups promote collective rather than selective good.

Answer 2

public interest are groups which seek to promote the interest of the people in general and look after common objectives for their betterment
they aim to help people and take up issue related to them.
they fight for social issues and social equality.