What is a chain?
The chain is a surveying unit of 66 feet, which is exactly 20.1168 meters. It is divided into 100 links of 7.92 inches each, and 80 chains make a mile.
The chain was devised by the English mathematician Edmund Gunter around 1620 and used to survey land. Ten square chains make exactly an acre, which is why surveyors liked it. GPS has replaced it for most work, though US public land surveys are still recorded in chains and links.
What is a meter?
The meter is the SI base unit of length and is equal to 100 centimeters or 1,000 millimeters. It was originally defined as one ten-millionth of the distance from the North Pole to the equator along the meridian through Paris. Since 1983 it has been the distance light travels in a vacuum in 1/299,792,458 of a second.