Insurance - Auto insurance question- PIP

I hope this is the right forum, but can anyone explain what PIP is and how to tell if I need it? My car insurance company sent me a PIP waiver form to sign for a new car, because I don't have PIP on my other policies, but I don't ever recall signing this before. Should I have PIP? It seems like if you have ever waived PIP before, then you and anyone in your family over 16 living with you are never covered, even on other policies if you or they are paying for it! Doesn't make any sense to me. This may be something that applies only in Maryland.

Personal Injury Protection (PIP)

PIP reimburses you or others named on policy for injuries in an auto accident. PIP reimburses you or others named on your policy for lost wages associated with an auto accident. This reimbursement will be made no matter who was at fault. This coverage is not mandatory. PIP can be denied if claims are not properly and timely filed, so it's important to contact your carrier immediately if there's an accident for PIP forms. Because some folks have health care insurance they tend to waive PIP, which may result in a lower premium. But, PIP covers lost wages and medical expenses for passengers not covered by health care insurance.

You can learn more about Maryland auto insurance law at http://www.autoinsurancelaw.com/maryland-auto-insurance-law.html Also, contact your insurance agent for clarification.