Small holes are drilled into the tree's trunk and a spigot is inserted to catch the sap. It is collected in buckets or barrels or fed directly into a tube and sent to a storage tank. Then the sap is immediately turned into maple syrup. Each tree usually produces about 10 gallons of sap a season. This is a precise science, if the temperature is too high the syrup will harden or crystallize, too low and it will spoil.
New technology uses reverse osmosis.
Overall, it takes about 40 gallons of sap to produce one gallon of maple syrup. By law, all maple syrup must be graded. Grades are defined by color, flavor and density. When they were first created over 100 years ago, the main purpose of collecting sap was to make maple sugar, not maple syrup. Thus, the highest and most expensive grades made the finest sugar.