Title insurance is available to protect sellers, purchasers, lenders and borrowers. It provides certainty by insuring the state of the title at it's registration date.
A title insurance policy costs a one-time premium for total coverage. It is typically used when there are questions about the state of the title, or when a portfolio of properties is being purchased. Title insurers in Canada are federally regulated.
Risks covered by title insurance:

Someone else owns or claims to own an interest in the property

Documents not properly signed, sealed or delivered

Fraud or forgery affecting the owner's interest in property

Defective registration of documents

Lack of access by car or by foot from the property to public roadway

Restrictive covenants limiting the use of the property

Liens on the property such as outstanding property taxes

Builder's liens (A charge against a property of money for the builder)

Un-marketability of title or land, including un-marketability due to defects revealed by a real property report

Easements

Work orders

Either the title holder or a neighboring property is forced to remove structures that violate zoning laws or the title

Adverse circumstances that would have been disclosed by a local authority search, such as an indication that a building permit had not been issued