There are broadly four types of Land Title in Thailand that are used as common evidence of land ownership, possessory rights an other interests in land:

Chanote (Title Deed)
A Chanote is a certificate for ownership of land. A person having their name shown on the deed has the legal right to the land, and can use it as evidence to confirm the right to government authorities.

The title deed has been issued by using GPS to set the area and boundaries of the land, which is a very accurate method. It is the long term goal of the Land Department that all land in Thailand will be covered under the Chanote title system. This is the most secure type of land title and is highly recommended.

Nor Sor Sam Kor (Confirmed Cerificate of Use)
This certifies that the person named on the certificate has the confirmed right to use the land, implying all requirements for the issuance of the title deed have been met and issuance of the deed is pending. They may be sold, leased, used as mortgage collateral and etc. The holder of this certificate cannot leave the land unattended for more than 12 years.

The Chanote and Nor Sor Sam Kor are the only titles over which registerable right of ownership or lease can exist and are as such the only ones that a prudent foreigner should consider.

Nor Sor Sam (Cerificate of Use)
Similar to the above Confirmed Certificate of Use except that not all of the formalities to certify the right to use have been performed. Before a transfer can be made, a notice of intent must be posted and then 30 days public notice is necessary before any change of status over the land can be registered.

Sor Kor Nung (Certificate of Possession)
This recognises that a person is in possession of land but the Certificate does not imply that there are any rights associated with the possession. It is not transferable, but a person in possession may transfer physical possession and the new possessor may apply for a new Certificate of Possession.

Ask to see a copy of the front and back of the land or condo title deed. A faithful translation of this will show you who the current owner is; if the property has any endorsements or liens; the shape, area and orientation of the property and border to a public property (such as a road, stream or the ocean).