Shell may refer to:

Architecture and design

Shell (structure) A shell is a type of structural element which is characterized by its geometry, being a three-dimensional solid whose thickness is very small when compared with other dimensions, and in structural terms, by the stress resultants calculated in ...

, a thin structure **

Concrete shell A concrete shell, also commonly called thin shell concrete structure, is a structure composed of a relatively Thin-shell structure, thin shell or Shell (structure), shell of concrete, usually with no interior columns or exterior buttresses. The ...

, a thin shell of concrete, usually with no interior columns or exterior buttresses ** Thin-shell structure

Science

Biology

* Seashell, a hard outer layer of a marine animal, found on beaches * Eggshell *

Nutshell A nutshell is the outer shell of a nut. Most nutshells are inedible and are removed before eating the nut meat inside. It covers and protects the kernel which may be edible. Usage Most nutshells are useful to some extent, depending on the circum ...

Exoskeleton An exoskeleton (from Greek ''éxō'' "outer" and ''skeletós'' "skeleton") is an external skeleton that supports and protects an animal's body, in contrast to an internal skeleton (endoskeleton) in for example, a human. In usage, some of the ...

, an external covering of some animals **

Mollusc shell The mollusc (or molluskOften spelled mollusk shell in the USA; the spelling "mollusc" are preferred by ) shell is typically a calcareous exoskeleton which encloses, supports and protects the soft parts of an animal in the phylum Mollusca, wh ...

***

Bivalve shell A bivalve shell is part of the body, the exoskeleton or shell, of a bivalve mollusk. In life, the shell of this class of mollusks is composed of two hinged parts or ''valves''. Bivalves are very common in essentially all aquatic locales, includi ...

***

Gastropod shell The gastropod shell is part of the body of a gastropod or snail, a kind of mollusc. The shell is an exoskeleton, which protects from predators, mechanical damage, and dehydration, but also serves for muscle attachment and calcium storage. Some ...

** Shell, of a

brachiopod Brachiopods (), phylum Brachiopoda, are a phylum of trochozoan animals that have hard "valves" (shells) on the upper and lower surfaces, unlike the left and right arrangement in bivalve molluscs. Brachiopod valves are hinged at the rear end, w ...

** Turtle shell

Physics and chemistry

Electron shell In chemistry and atomic physics, an electron shell may be thought of as an orbit followed by electrons around an atom's nucleus. The closest shell to the nucleus is called the "1 shell" (also called the "K shell"), followed by the "2 shell" (or ...

or a principal energy level of electrons outside an atom's nucleus *

Nuclear shell model In nuclear physics, atomic physics, and nuclear chemistry, the nuclear shell model is a model of the atomic nucleus which uses the Pauli exclusion principle to describe the structure of the nucleus in terms of energy levels. The first shell m ...

, a principal energy level of nucleons within an atom's nucleus *

On shell and off shell In physics, particularly in quantum field theory, configurations of a physical system that satisfy classical equations of motion are called "on the mass shell" or simply more often on shell; while those that do not are called "off the mass shell", ...

, quantum field theory concepts depending on whether classical equations of motion are obeyed

Mathematics

Spherical shell In geometry, a spherical shell is a generalization of an annulus to three dimensions. It is the region of a ball between two concentric spheres of differing radii. Volume The volume of a spherical shell is the difference between the enclosed volum ...

Organisations

* Shell plc, a British multinational oil and gas company ** Shell USA **

Shell Australia Shell Australia is the Australian subsidiary of Shell. Shell has operated in Australia since 1901, initially delivering bulk fuel into Australia, then establishing storage and distribution terminals, oil refineries, and a network of service sta ...

Shell Canada Shell Canada Limited (french: Shell Canada Limitée) is the principal Canadian subsidiary of British energy major Shell plc and one of Canada's largest integrated oil companies. Exploration and production of oil, natural gas and sulphur is a maj ...

Shell Nigeria Shell Nigeria is the common name for Shell plc's Nigerian operations carried out through four subsidiaries—primarily Shell Petroleum Development Company of Nigeria Limited (SPDC). Royal Dutch Shell's joint ventures account for more than 21% of ...

Shell corporation A shell corporation is a company or corporation that exists only on paper and has no office and no employees, but may have a bank account or may hold passive investments or be the registered owner of assets, such as intellectual property, or s ...

, a type of company that serves as a vehicle for business transactions

Computing

Shell (computing) In computing, a shell is a computer program that exposes an operating system's services to a human user or other programs. In general, operating system shells use either a command-line interface (CLI) or graphical user interface (GUI), depending ...

, a type of user interface ** Command-line interface, sometimes referred to as command shell **

List of command-line interpreters In computing, a command-line interpreter, or command language interpreter, is a blanket term for a certain class of programs designed to read lines of text entered by a user, thus implementing a command-line interface. Operating system shells ...

, programs occasionally referred to as shells **

Web shell A web shell is a shell-like interface that enables a web server to be remotely accessed, often for the purposes of cyberattacks. A web shell is unique in that a web browser is used to interact with it. A web shell could be programmed in any pro ...

, interface that enables a web server to be remotely accessed *

Read–eval–print loop A read–eval–print loop (REPL), also termed an interactive toplevel or language shell, is a simple interactive computer programming environment that takes single user inputs, executes them, and returns the result to the user; a program written ...

, also known as a language shell *

Shell account A shell account is a user account on a remote server, traditionally running under the Unix operating system, which gives access to a shell via a command-line interface protocol such as telnet, SSH, or over a modem using a terminal emulator. S ...

, a user account on a remote server *

Secure Shell The Secure Shell Protocol (SSH) is a cryptographic network protocol for operating network services securely over an unsecured network. Its most notable applications are remote login and command-line execution. SSH applications are based on ...

, cryptographic network protocol *

Shellsort Shellsort, also known as Shell sort or Shell's method, is an in-place comparison sort. It can be seen as either a generalization of sorting by exchange (bubble sort) or sorting by insertion ( insertion sort). The method starts by sorting pairs of ...

or Shell sort, a sorting algorithm by Donald Shell * Shell, an empty expert system

Entertainment

* ''Shell'' (film) *

Shell (theater) In theater, a shell (also known as an acoustical shell, choral shell or bandshell) is a curved, hard surface designed to reflect sound towards an audience. Often shells are designed to be removable, either rolling away on wheels or lifting into ...

, a curved surface for reflecting sound * The Shells, a musical group * "Shells" (''Angel''), a TV episode * Shell, a receptacle used in the

Shell game The shell game (also known as thimblerig, three shells and a pea, the old army game) is often portrayed as a gambling game, but in reality, when a wager for money is made, it is almost always a confidence trick used to perpetrate fraud. In con ...

Places

* Shell, Ecuador * Shell, Wyoming, United States * Shell Lake (disambiguation), several places

Weaponry

* Shell (projectile), an explosive device fired from artillery * Shotgun shell, a type of shotgun ammunition

Persons with the surname Shell

* Art Shell (born 1946), American football player and coach * Brandon Shell (born 1992), American football player *Donald Shell (1924–2015), American computer scientist * Donnie Shell (born 1952), American football player * George W. Shell (1831–1899), U.S. Representative from South Carolina * Karl Shell (born 1938), American economist

Other uses

* Racing shell, a watercraft * Shell (machinery), each half of a two-piece plain bearing * Coverage shell, the number of defenders guarding the deep portion of the field in American football *Conchiglie, a type of pasta