What is Corporate Tax that Chancellor lowered?

Their is uproar about Osbourne lowering the Corporate Tax from 50p to 45p. But what exactly is this Corporate Tax. Who pays this tax. How is this Tax calculated. How much difference does it make lowering this tax from 50p to 45p.

Tories wanted to lower this tax even lower but didn't due to uproar it would cause. So why is the city so interested in getting this tax axed.

What is a VPN?

VPN is (Virtual Private Network) were first used by companies to enable their employees to securely access internal systems such as email remotely (e.g. from home or while on business trips). Today they are increasingly being used for personal use by individuals to protect their privacy while online in public places (e.g. when using the wi-fi connection in a cafe) or in a country where the internet is censored / blocked (e.g. China, Saudi Arabia…).