Two of the main wildfire terms that can be commonly confused are "contained" and "controlled." A contained fire is when first responders establish a control line around the perimeter that is expected to stop the spread of flames, according to the New York Department of Environmental Conservation. SEE IT: WILDLAND FIREFIGHTERS LEAP FROM 3,000 FEET IN THE AIR TO COMBAT THE SPREAD OF WILDFIRESA fire can remain out of control even when contained. WATCH: DRAMATIC VIDEO SHOWS FREIGHT TRAIN, CREW CAUGHT IN CANADIAN WILDFIRESDespite this, the fire may escape the established control lines if conditions change. SCIENTISTS SAY IT'S COMPLICATEDA controlled fire is one in which there is little threat that a specific fire will escape the established control lines.