Technology / Computers / Shell: Just like the shell of an egg is the outermost layer, in computer technology, this refers to the outermost layer of a program. Operating systems and applications sometimes provide an alternative shell to make interaction with the program easier. For example, if the application is usually command driven, the shell might be a menu-driven system that translates the user's selections into the appropriate commands. Sometimes called command shell, a shell is the command processor interface. The command processor is the program that executes operating system commands. The shell, therefore, is the part of the command processor that accepts commands. After verifying that the commands are valid, the shell sends them to another part of the command processor to be executed.
Science / Chemistry / Valence Shell: The shell corresponding to the highest value of principal quantum number in the atom. The valence electrons in this shell are on average farther from the nucleus than other electrons; they are often d MORE
Science / Chemistry / Subshell: A set of electrons with the same azimuthal quantum number. The number of electrons permitted in a subshell is equal to 2ell + 1. MORE