An ISA (Individual Savings Account) is a great investment vehicle that you need to take full advantage of. We all know just how important it is to save money and to invest for the future, but for most it seems like a distant dream - buried under credit card debt.Saving money is more than just a wise thing to do with your money. Its necessary and many people face a bleak retirement. Saving for your retirement is something you need to start as soon as possible and using an ISA is a great way to do it. One of the main benefits of an ISA is that its a tax free investment. You don't even need to declare the investment (to the maximum allotted amount) to the IRS.Although there is a limit on the amount you can save in your ISA, if you do it every year it can quickly add up. For many people, having an ISA and knowing that they can save tax free often encourages them to save the full amount. If you are someone who is struggling with getting yourself to save every month, then just having an individual savings account can be encouragement enough.ISA's also allow you to invest in stocks. Even after the global financial crises, the stock market is still the best investment vehicle with the highest returns on average. ISA's are designed to encourage you to invest in the stock market and you can invest your entire ISA limit in stocks and shares. Most mutual fund providers will allow you to invest in their stock portfolios which can be an easy way to invest in the stock market with minimal effort and maximum savings as this too will be exempt from tax.The sooner you start using your ISA the better. By making the full saving every year, it soon adds up and before you know it you can build a really nice nest egg.Read more about savings accounts and learn about the best cash ISA options.