The UK's Companies Act 2006 makes a number of significant changes to the law on shares and share capital, though many provisions of the old law are retained. Some changes are simplifications to the law for UK private companies (notably on financial assistance, share capital reduction, and company buy-back of own shares, as well as the abolition of authorized capital). Other provisions are entirely new, such as treasury shares. The whole structure is informed and constrained by the provisions of the Company Law Directives, which are principally applicable to public companies. This book will be based on Parts 17, 18, 20, 21, and 22 of the Companies Act 2006, together with the provisions of the new Table A and Table C. However, even these extensive UK legislative provisions do not deal with all the issues which can arise, and case law doctrines, such as improper purposes for issuing shares, will also be considered. In addition, case law on those provisions which have not changed will continue to be relevant.