Individual Savings Accounts (ISAs) provide a tax-efficient way to save and invest, allowing up to £20,000 in contributions for the 2018/19 tax year. Different types of ISAs, such as cash ISAs, stocks & shares ISAs, and innovative finance ISAs, cater to various savings goals, including home purchasing and flexible investing. It's crucial to utilize the annual allowance before the deadline of April 5, 2019, as it cannot be carried over into the next tax year.