People toss the term "full coverage" around like it's as simple as checking that non-existent box on a form and initialing the change. There are several different segments of coverage that insure you in different ways. Basic liability insurance is usually what's needed to legally drive a car and it also has three parts to it, hence the three numbers like 100/300/100, and it means, in this example $100,000 per person you affect, $300,000 total to people you affect and $100,000 in property damage of those you affect. It doesn't do squat for you except keeping you from getting sued for up to those amounts. If you're a homeowner or someone with substantial assets, make those number big.
Additional coverage includes comprehensive, and you can usually add no-deductible glass coverage. Now, your insurance company probably won't allow you to claim under comprehensive if someone slams a car into yours (that would be collision coverage), but they would cover under comp if a tree fell on it, or let's say, someone tosses a propane cylinder into a campfire and it blows up, sending a log-missile through your back window (as happened to me). Your insurance company will probably suggest that you carry a high deductible to save you money. I don't subscribe to that theory, since I have asked them to quote me the difference between a $100, $500 and $1,000 deductible and it didn't make sense to me, and so I have a tiny $100 deductible on all of mine, with the window glass at zero deduct.
Collision coverage covers your vehicle in the event of a, well, collision, or as I said above, if your parked car is determined to have been hit by another vehicle (that part pisses me off; I think that should be comprehensive). The issue of ACV, SCV, etc was covered in the post above mine and is worth understanding. You might also want to do some research yourself into the term "diminished value" to understand what happens when you have a vehicle repaired after an accident. This coverage becomes less sensible as a vehicle ages, since it is somewhat costly and your vehicle becomes worth less in their eyes. Deductibles also can be selected at various levels for collision coverage.
Medical coverage for yourself and your passengers. They can sue you if they don't have insurance and they get hurt in or because of your vehicle. Sometimes a homeowners umbrella policy can protect you from passenger's lawsuits against you, see your insurance professional to clarify that. I do not carry this coverage.
Underinsured motorist coverage. Your insurance company picks up where the other person's cheesy coverage runs out. Pretty reasonable cost for this coverage.
Uninsured motorist coverage. Your insurance pays for their complete lack of being an upright citizen and actually buying insurance in the first place. If you live in AZ, where it seems like half of everybody on the road is somehow uninsured, and they somehow get away with it, I'd call this one a no-brainer.
Roadside assistance or towing. Reimburses you for a tow you had to pay for, etc.
Rental car 1 and 2. Differing levels of reimbursement for needing a rental car while your car is being repaired due to an insured claim. This is not coverage for a car you rent on vacation. Your regular policy almost always covers that, and the credit card you use to rent the car on vacation may also offer some coverage as well. I don't carry this coverage, since I have several vehicles. Sometimes more than one of them actually run.
So, ask your buddy what he means by "full coverage" the next time the subject comes up. There are most certainly other coverages available that I didn't remember, and you may or may not want or need all the ones I did or did not list. Be informed, ask your agent questions and make them quote you policies with different deductibles so you can really see if the savings they are pushing make sense to you. Heck, if a guy who repairs appliances (me) can spout this much nonsense about insurance, it probably means I took a little time to investigate what it is that I'm paying SO much money for every month.
John B.