What is an ISA?
An ISA is a tax free wrapper that allows a person to save money or invest in stocks and shares. The investment must be made through an approved ISA managing agent and is limited to either one Maxi ISA or two Mini Isa's in any one tax year which begins in April.
Isa Managers are typically Banks and Building Societies and must be authorised by the Financial Services Authority. It should be noted that approval does not give any sort of guarantee about future perfomance of your investment nor guarantee a satisfactory return for you.
The investment rules mean that you can invest into your yearly ISA up to the limits for each type but once the money is withdrawn it cannot be replaced so ISA's are not suitable for temporary savings or use as a normal savings account.