Original restaurant service began with a listed menu and the patron ordering his or her meal from there.  This allowed the establishment to control the portion size and the selection of food, therefore maximizing the profit from each plate served.  Once self-service buffet meals became main stream, restaurants were able to improve their profit margins through volume sales instead as they could reduce staffing to a minimum level and save much on employee wages.  

During a buffet meal, a customer is entitled to select as much food as they wish for a fixed price.  There still may be wait staff in this type of restaurant atmosphere to remove dirty dishes and provide drink refills, but there is typically not a menu, although this depends on the restaurant.  Runners replenish the buffet as necessary, bringing out the dishes that the cooks prepare in bulk.  The restaurant may be totally a self-serve style and each hot or cold item usually has tongs or slotted spoons.  There may be staff assigned to carve meats like roast and turkey or a homemade omelet station for made-to-order dishes.  Most buffets arrange their collections of food into specific sections such as meats, vegetables, salads and desserts.

According to Kamloops Restaurants, the term "smorgasbord" is thought to mean all-you-can-eat buffet and often credited to the Swedish.  The word literally translates to "sandwich table" and it was developed to allow patrons a chance to sample small portions of food.  True smorgasbord begins with cold fish based appetizers and then progresses into sandwiches, meat dishes and eventually dessert.  Nowadays, modern buffet may offer hot meats, cold salads and a variety of mouth watering desserts.  The diner can decide the amount of food to take and what order to choose it in.  This does cause some loss of money for the restaurant on with overindulgent diners, although, this is considered to be an acceptable loss.  Many other diners do not choose the most expensive items such as or eat copious amounts of food.

Typically a buffet restaurant orders much of their supplies from middleman or wholesaler who can purchase food in bulk at a substantial discount.  The meal price of the buffet usually helps the establishment recoup the majority of their raw food expenses and the volume of patrons helps to cover the cost of staffing wages along with other bills.

Buffet style eating has become hugely popular for group events such as weddings and company Christmas parties for example.  The ability for people to pick their own entrees and side dishes as well as control their individual portion control has become widely advantageous for the restaurant industry.   Many steakhouses and a variety of restaurants combine menu and buffet style options for their patrons.

The original buffet restaurant most likely started in the casinos in Las Vegas.  The buffet provided an ideal solution for casino owners to keep gamblers inside of the building and presented another attraction for those passing by the hotel or casino.  Vegas today is still well-known today for its fancy buffet arrangements along with the musical and gambling entertainment.  Casino owners can easily provide their customers with the maximum amount of food and the least amount of staffing.