Tax-free ISAs are open to all UK residents over the age of 16.  There are limits on the amount you can pay in each year.
The total ISA allowance per adult for 2015/16 is £15,240. Whether you open one ISA account or more than one, being cash ISA, stocks and shares ISAs or both, the most you can save into ISAs per financial year (April to April) is £15,240. ISAs are exempt from income tax and capital gains tax on the investment returns, and no tax is payable on money withdrawn from the scheme either. Cash and a broad range of investments can be held within the arrangement, and there is no restriction on when or how much money can be withdrawn.
Money held within an ISA is protected by the FSCS. (Financial Services Compensation Scheme) up to a maximum of £85,000. Stocks and shares ISAs allows you to invest in cash, unit trusts, OEICs, certain investment trusts, shares, government bonds, corporate bonds and other public debt products.
Junior ISAs (JISAs) allow you to save up to £4,080 per financial year for children , they are available as cash and stocks and shares ISAs to UK Residents only. Money cannot be withdrawn until the child is 18. A child from the age of 16 can open their own account.

Lifetime ISA

It’s a savings account that allows you to save for a property or retirement without paying tax on the interest you earn. It also offers a government bonus to boost your savings – equal to 25% of everything you save. The bonus will be added each year, so you can earn interest on it. It will be yours to keep either when you buy a property or when you reach the age of 60.
The Isa will be available from April 2017.