The .bss segment stores all uninitialized global, static, and external variables (declared with extern keyword). Global, external, and static variable are by default initialized to zero. This section occupies no actual space in the object file. it is merely a place holder. uninitialized variables do not have to occupy any actual disk space in the object file.
The use of the term .bss to denote uninitialized data is universal. It Stands “Block Storage Start”.
