How can one lose rights to a trademark?

One can lose rights to a trademark if a mark that was once distinctive becomes the common generic name for a product or service. This may occur when a trademark owner does not properly police the use of his or her mark. In one example, the word “escalator” was once a trademark for a brand of moving stairs, but because of improper policing of the mark it has become generic. The name of a product or service should always be capitalized. It should always be used in conjunction with the common generic name of the goods or service as in “Ford motor car” or “XYZ brand of toilet tissue”. Never use a trademark as a verb; it is improper to “Xerox a document” – instead, one photocopies a document using a Xerox brand copy machine.