What is the shell?
In the most general form, the shell is an outer layer. But in order to more fully answer the question of what a shell is, one should consider the multifaceted meaning of the term.
The shell is ...
There are at least three areas in which the term "shell" is used. Each of them should be considered:
In astronomy, a shell is a gaseous region that surrounds one or more astronomical objects, for example, stars.
Strength of materials
In the mechanics of a deformable solidthere is a section called "resistance of materials." In this section, the term "shell" is used. By it is meant a certain geometric form of the body. In this case, one of the dimensions of the body must be considerably less than the other two.
In programming is often usedthe term "shell". In this case, we mean a certain software module that creates an interface for the user to work with the functions of the operating system. That is, when we talk about the shell of the operating system, it is about the interpreter of its commands.
Anyway, definitions in all spheresconfirm that in the most general form any shell is a certain surface layer covering something. You can also understand this term verbatim, for example, when mentioning the Earth's shell, shell of grain, shell bullets, etc.
Many other interesting definitions you can find in the special section of our site - Definitions.