A limited lifetime warranty is an agreement between someone who purchases a product and the manufacturers of that product. This agreement entitles the purchaser to recompense if the product does not meet certain agreed specifications.
All warranties have a time period for which they are valid. The fact that a warranty is limited means that the extent of the liability of the manufacturer is set only to what is specified in the warranty itself. For example, the manufacturer may be liable if the product suffers technical failure, but not if the purchaser damages the product through his own actions.
The lifetime of the warranty refers to the period of time in which the warranty remains in force, starting from the date the purchaser buys the product. The lifetime in question is rarely the lifetime of the purchaser, but rather the length of time the manufacturer continues to make the product. Once a product is discontinued, the length of time the manufacturer remains liable under the warranty is specified in the warranty documentation.
In legal terms, a warranty is an assurance from the manufacturer of a product to the purchaser that the product will meet certain specifications. Depending on the legal jurisdiction and the nature of the product and transaction a warranty may by implied or expressed by both parties.