Hello, while studying crystalline solid structure one thing i don't understand. What does the "basis" means. Lattice seems clear but the basis comes along with problem. The problem arise in this case : CsCl structure is not BCC (Body Centered Cubic). It is SC (Simple Cubic) with two basis. That what says in the book. My question is, if i consider CsCl is not BCC and it can be represented by SC with two basis (CS+ and Cl-) then why can't we imagine or consider original BCC structure as a combination of SC with two basis (two Fe atoms). But it is clearly declared that BCC is an unique Bravis lattice. Can anyone clear me out?