Carbon Canister
WARNING: This page does not describe the selected car, but rather 33 other vehicles, including the 2002 Saturn Vue, 2002 Pontiac Montana, 2002 Pontiac Aztek, 2002 Oldsmobile Silhouette, and 2002 Oldsmobile Bravada. However, it is still accessible from the selected car via links, so may be relevant.
Evaporative fumes from the fuel tank are vented through hose(s) into a canister containing activated carbon. Activated carbon absorbs and holds fuel vapors when engine is not operating. When engine is started and engine speed is greater than idle (purge at idle would cause too rich a mixture), engine vacuum draws fuel vapors from canister into engine. A vacuum canister purge valve or purge control solenoid regulates vapors through this purge line.
Carbon canisters are open in design. When engine is started, engine vacuum draws outside air into canister either through top or bottom, then through a filter in bottom of canister. This helps to purge vapors from the activated carbon.