If you do not have a will then you do not know, for certain, who will be making decisions about your property and possessions after your death. And the decisions that are made may not fall in accordance with your wishes.
In general if there is not a will in place then the rules of intestacy apply. More importantly your friends and family could face the prospect of sorting out who gets what and what goes where at a particularly stressful time.
By writing a will you will have a legal document that lays out what you want to happen to your estate after you die. This means that your possessions such as your home (minus mortgages or any other charges on it), your money, your belongings and any other proceeds will go to those you want them to go to (after any outstanding debts have been cleared).
To ensure this happens you will appoint at least one executor of the will and they will be responsible for overseeing the administration of the will and that the terms of the will are carried out. This may be an obvious statement but dying without a will can cause some serious problems for your nearest and dearest, and the way to avoid this is to have a will professionally written for you. Sooner rather than later.
So, why have a will? Because you care about your families future!