CBSE Class 11-science Answered

Any particular electron will be found in a region of space known as an orbital.

The circular path of rotation of electron around the nucleus is called an orbit, whereas the region around the nucleus of an atom where probability of finding the electron is maximum is called orbital.

First, there are the main shells of the atom, and these are numbered 1, 2, 3, 4, etc. (or like some doing it alphabetically K, L, M, N, ...). 

Each shell holds subshells. The types of subshellsare labeled like this: s, p, d, f,  etc.