Demo trading is really important for the both new and experienced traders. A demo trading platform is quite similar to the real platform. However, you will not get the feeling of investing real money.
You can trade with virtual money which as no monetary value at all. Remember, you can not withdraw your profit amount from the practice account. A risk free trading environment where you can test all the trading strategies, can use stop-loss to protect you from trading risk.
You will see that almost all the broker is giving the facility to trade in demo account before opening a live account. You know why they do this to you? Because they wants to make you understand what is the trading and you can apply your knowledge in to the practical field.
So, for me a demo account is not only important tools for traders but also a life saver.