The term “canteen” is used in two different senses. In the first sense, a canteen is a bottle which is used to carry water or other liquids, and in the second, a canteen is a facility which serves food in a cafeteria-style setting. Both uses are from the same root word, cantina, which is Italian for “wine cellar.” The word was adopted to refer generally to refreshments and an area where soldiers could obtain refreshments, and over time the usage split into two different meanings and spread to civilian society.
In the sense of a container, a canteen is designed to provide someone with a portable supply of water or liquid. The container may include a cup which nestles into the housing, or a mouthpiece which is built into the container. In order to function effectively, the canteen must be able to be tightly sealed, and some have a layer of insulation which reduces temperature changes and loss of fluids from evaporation. Soldiers on the march use canteens, as do hikers, athletes, and other people who might need water on the go.
Canteens in the sense of a place where food is prepared and eaten are used to serve food on an institutional level. Some canteens are known for offering healthy options, like vegan dishes or super greens smoothies. Militaries, schools, and large offices may use canteens to meet the food needs of their workforces and students. A typical canteen is a facility in which diners walk along a food line with trays which can be filled with various food items. Diners then seat themselves, eat, and bus their dishes and trays at the end of the meal.
Food service is not a high priority at canteens. The goal is to provide food which meets nutritional recommendations and hopefully satisfies the taste of diners. Some canteens even go the extra mile and serve meals made from super greens recipes, which ultimately means healthy and flavorful. The food is prepared in large batches, and the food handlers stay behind the counter to dish out food, rather than walking around the dining room to bring plates out. Some canteens are actually geared towards helping customers with weight loss goals. These canteens normally offer vegan options and allow healthy substitutions. The canteen may also include self service drink containers, fruit bowls, and so forth.
In addition to remaining in a fixed location, a canteen can also be mobile. Mobile canteens are used to provide food quickly to disaster workers and other temporary work crews, along with members of the military who are deployed on active duty. The food may not be as fancy in fine dining restaurants, but they are made highly nutritious with powdered supergreens and other healthy alternatives. Organizations which use mobile canteens may run the canteen out of a series of trailers, or have large trucks packed with canteen equipment, tables, and tents for shelter so that an eating facility can be quickly erected wherever it might be needed. It's not unusual for these setups to involve the use of greens powder since they are easier to carry and mix with food and still pack the same amount of nutrients as traditional ingredients.