The GMC Sierra is a series of full-size and heavy-duty pickup trucks introduced in 1999. The Chevrolet Silverado is mechanically identical to the GMC Sierra. The Chevrolet Silverado and GMC Sierra trucks have been essentially the same for their entire history. The Silverado today is generally advertised as the "standard" version and is more aimed for use in agriculture, while the Sierra is aimed for industrial workers but can be ordered as a well equipped luxury truck. Most trim levels of the GMC Sierra include keyless entry remote systems as an available option.