This document provides an overview of share capital for companies incorporated in England, Wales or Scotland. It explains that share capital refers to the capital contributed by shareholders through their purchase of shares in the company. It also outlines what is meant by authorised share capital, issued capital, allotment of shares, and requirements around altering share capital and notifying Companies House of changes. The document is intended as an initial guide to the subject and readers are advised to seek professional advice on company law.