Loading and unloading ships requires knowledge of the operation of loading equipment, the proper techniques for lifting and stowing cargo, and correct handling of hazardous materials. In addition, workers must be physically strong and able to follow orders attentively. To unload a ship successfully, many longshoremen are needed. There is only a limited amount of time that a ship can be at a port, so their work must be completed quickly.

In earlier days before the introduction of containerization, men who loaded and unloaded ships had to tie down cargoes with rope. A type of stopper knot is called the stevedore knot. The method of securely tying up parcels of goods is called stevedore lashing or stevedore knotting. While loading a general cargo vessel, they use dunnage, which are pieces of wood (or nowadays sometimes strong inflatable dunnage bags) set down to keep the cargo out of any water that might be lying in the hold or are placed as shims between cargo crates for load securing.

Today, the vast majority of non-bulk cargo is transported in intermodal containers. The containers arrive at a port by truck, rail, or another ship and are stacked in the port's storage area. When the ship that will be transporting them arrives, the containers that it is offloading are unloaded by a crane. The containers either leave the port by truck or rail or are put in the storage area until they are put on another ship. 

Once the ship is offloaded, the containers it is leaving with are brought to the dock by truck. A crane lifts the containers from the trucks onto the ship. As the containers pile up on the ship, the workers connect them to the ship and to the other already-placed containers. The jobs involved include the crane operators, the workers who connect the containers to the ship and each other, the truck drivers that transport the containers from the dock and storage area, the workers who track the containers in the storage area as they are loaded and unloaded, as well as various supervisors. Those workers at the port who handle and move the containers are likely to be considered stevedores or longshoremen.

Before containerization, freight was often handled with a longshoreman’s hook, a tool which became emblematic of the profession (mostly on the west coast of the United States and Canada).

Traditionally, stevedores had no fixed job, but would arrive at the docks in the morning seeking employment for the day. London dockers called this practice standing on the stones, while in the United States it was referred to as shaping up or assembling for the shape-up, or catching the breaks.[citation needed] In Britain, due to changes in employment laws, such jobs have either become permanent or have been converted to temporary jobs.

Dock workers have been a prominent part of the modern labor movement.