A freighter, barge, or cargo ship was the term given to any spacecraft that was used to transport freight or cargo (such as parts and supplies). Both legitimate businesspersons and smugglers could be found captaining such transports. From the beginning of space travel, freighters were needed to move supplies to all reaches of the galaxy. Freighters usually traveled with hyperdrives because people would often pay more for quick delivery.
Freighters were used mainly for trade. Although very few fought in great battles, many freighters did see action. Smugglers and legitimate traders alike had some tangles now and then, and freighters were often armed and shielded so that they could resist attempts on their cargo.
Smuggling was a very prominent criminal fringe activity in the galaxy that involved the transportation of contraband between planets and systems. To do this, a freighter generally of small size such as the Millennium Falcon, was required to transport the contraband past planetary security forces. Some examples of contraband include spice, blasters and medical supplies.
Smugglers often added upgrades to their ships so that they could beat competitors and outwit planetary security forces. Almost every smuggler's vessel had improved light speed and sub-light speed drives for increased speed as well as boosted weapons systems to fight their way out of tough situations. Another of the most prevalent modifications to a smugglers freighter were numerous secret compartments to hide contraband from security checks while legitimate cargo occupied the cargo bays. On the Millennium Falcon, these consisted of removable floor plates.
Some freighters became so heavily modified that the mess of cross-wired and non-traditional parts prevented starship mechanics from working on them effectively. The smugglers themselves were therefore required to have a detailed knowledge of freighter mechanics and electronics to be able to keep their vessels in working order. Most smugglers preferred it this way as they didn't trust anyone tampering with their prized possessions.
Most smugglers freighters required a crew of more than one and as such most smugglers hired a copilot, such as Chewbacca on the Millennium Falcon or the droid LE-BO2D9 aboard the Outrider. To a smuggler, their freighter was everything; their job, their home, their lives. Many smugglers lived in their freighters as they had no terrestrial home.