First things first, do you even know if your parents have an estate plan in place? If you do, great, you're one step ahead....if not, well, you're going to want to find out.
When we talk about having an estate plan most people know the importance of having a Will. A Will is going to outline what you want to happen to your property and money after you die. It will appoint an executor (if that's going to be you, be prepared...it is NOT an easy job). Not only will your Will (will your Will...stupid word confusion!) out line who your assets go to, it can also assign guardians for any non-adult children and your funeral instructions. I highly recommend using a lawyer to do your Will; yes it's going to cost a bit of money to get done but it will cost a lot less than not having a Will or having a poorly written Will that could be disputed in court. A good estate lawyer will know what to ask to ensure everything is covered and your legacy will end up where you want it. There's a few stipulations when it comes to how money is dispersed within an estate. You have to provide for your spouse and any dependents (this includes underage children as well as adult children who can't care for themselves...I said can't, not wont). The amount will really depend on how big your estate is, if it's large it might just be a small portion but if the estate is small it could be the whole thing. Basically, you can't leave everything to your dog and nothing for your husband!
Along with your Will there are a couple of other documents you'll want to get prepared, these are a Power of Attorney and Personal Directive. Unlike a will, which is for after you die, a POA and a PD are for when you are still alive and they will let you still have a certain level of control when you aren't able to make competent decisions.
A Power of Attorney is the document that appoints a person (usually a primary and an alternate) who will act as the decision maker for your finances and property if you become incapable of making such decisions for yourself. You want to do your POA when you are in good health but it will only come into affect after a doctor or other medical professional (you can get specific about certain qualifications or number of opinions) deems you unfit to make decisions. Once that happens the person you have appointed as your attorney will take over the decision making, so make sure it's someone you trust and can handle that responsibility.
A Personal Directive is similar to a POA but it deals with health matters. Here you will be assigning someone (often the same person) to make decisions for you regarding health care and personal needs if you are no longer able to make them yourself. A PD will let you still be the boss even when you can't actually make the decisions. Included in your Personal Directive will be directions on what sort of measures to take (extensive vs do not resuscitate orders), where you will live (at home if possible or a nursing home), etc.
Not having a Power of Attorney of Personal Directive in place can make things really difficult on your family. They will have to go to court to have a trustee/guardian appointed for you and that's a lengthy, costly and invasive process. Again, this is going to cost you more in the long run than just getting your estate plan done now.
Those are the three basic components of a comprehensive estate plan and you want to make sure your parents have all three in place. It's not going to be an easy conversation but knowing they have things in order (and up to date) and having at least a basic idea of what to expect will make an extremely challenging time a little more straight forward. If your parents don't have a Will, POA and PD or they need to be updated, I suggest you hassle them mercilessly until until you wear them down and they just do it. Maybe remind them that this is their chance to keep on parenting you even after they are gone...