Ration

Rations were controlled portions of certain foodstuffs, distributed in times of emergency or scarcity, or in situations where carrying large amounts of food was impractical. Rations would often contain carefully balanced mixes of nutritional supplements designed to nourish the body in place of normal food. A common problem with such rations was that their taste left much to be desired.

Rationing in time of crisis or scarcity
Rationing food and water was a strategy employed in many cultures to deal with scarce supplies and shortages. If the situation grew worse, it might become necessary to cut the rations. Rationing was sometimes necessary on newly-colonized planets.

During the last years of the planet Kataan, water was rationed to deal with droughts. 

In an alternative 1944, Nazis occupying New York rationed meat for the local population, and subsequently cut the rations multiple times.

Food in the San Francisco Sanctuary Districts was distributed based on a system of ration cards. 

Carmen Davila, a colonist on Melona IV, saved a ration of dried chicken curry for a very special occasion. 

During the USS Voyager's time in the Delta Quadrant, Captain Janeway and her crew were forced to invent a system of replicator rationing in order to save energy and supplies. 

Field rations, combat rations and emergency rations
During away missions and many other types of deployments, rations were widely used to feed personnel, as it obviously not always possible to reach a mess or replicator for meals. While such rations were used for practical reasons rather than due to scarcity, often shuttles and isolated facilities would also contain emergency rations, which could keep a person alive until help arrived should they find themselves cut of from their support structure. This was standard practice in Starfleet and amongst many other cultures.

Klingons used ration packs during planetary excursions, and left a few empty ones on an unnamed planet. 

The Federation also made extensive use of rations, who went by many nicknames. Starfleet rations were specifically, "concentrated vitamin-enriched nutritional supplements." . Although use of these rations were considered by many Starfleet officers to be a necessary evil, Julian Bashir developed a candy bar with superior nutritional value. 

Other types of rationing
Prisons would often distribute food to their inmates in the form of prison rations. 22nd century Enolian prison rations were particularly infamous for their bad taste. 

Specific ration packs

 * TKL rations
 * Ration pack 5
 * Nutri-pak