What is Title Insurance?

Legal Definition
Title insurance is a form of indemnity insurance predominantly found in the United States which insures against financial loss from defects in title to real property and from the invalidity or unenforceability of mortgage loans. The vast majority of title insurance policies are written on land within the United States. Unlike some land registration systems in countries outside of the US, the US states' recorder of deeds generally do not guarantee indefeasible title to those recorded titles. Title insurance will defend against a lawsuit attacking the title, or reimburse the insured for the actual monetary loss incurred up to the dollar amount of insurance provided by the policy.

The first title insurance company, the Law Property Assurance and Trust Society, was formed in Pennsylvania in 1853. Typically the real property interests insured are fee simple ownership or a mortgage. However, title insurance can be purchased to insure any interest in real property, including an easement, lease or life estate.

There are two types of policies – owner and lender. Just as lenders require fire insurance and other types of insurance coverage to protect their investment, nearly all institutional lenders also require title insurance [a loan policy] to protect their interest in the collateral of loans secured by real estate. Some mortgage lenders, especially non-institutional lenders, may not require title insurance. Buyers purchasing properties for cash or with a mortgage lender often want title insurance [an owner policy] as well. A loan policy provides no coverage or benefit for the buyer/owner and so the decision to purchase an owner policy is independent of the lender's decision to require a loan policy.

Title insurance is available in many other countries, such as Canada, Australia, the United Kingdom, Mexico, New Zealand, Japan, China, Korea and throughout Europe. However, while a substantial number of properties located in these countries are insured by U.S. title insurers, they do not constitute a significant share of the real estate transactions in those countries. They also do not constitute a large share of U.S. title insurers' revenues. In many cases these are properties to be used for commercial purposes by U.S. companies doing business abroad, or properties financed by U.S lenders. The U.S. companies involved buy title insurance to obtain the security of a U.S. insurer backing up the evidence of title that they receive from the other country's land registration system, and payment of legal defense costs if the title is challenged.
-- Wikipedia
Legal Definition
Insurance against loss or damage resulting from defects or failure of title to a particular parcel of realty, or from the enforcement of liens existing against it at the time of the insurance. This form of insurance is taken out by a purchaser of the property or one loaning money on mortgage, and is furnished by companies specially organized for the purpose, and which keep complete sets of abstracts or duplicates of the records, employ expert title-examiners, and prepare conveyances and transfers of all sorts. A "certificate of title" furnished by such a company is merely the formally expressed professional opinion of the company's examiner that the title is complete and perfect (or otherwise, as stated), and the company is liable only for a want of care, skill, or diligence on the part of its examiner; whereas an "insurance of title" warrants the validity of the title in any and all events. It is not always easy to distinguish between such insurance and a "guaranty of tiile" given by such a company, except that in the former case the maximum limit of liability is fixed by the policy, while in the latter cast the undertaking is to make good any and all loss resulting from defect or failure of the title.
-- Black's Law Dictionary
Legal Definition
Policy insuring mortgagee or owner against loss by defects in title.