What are the COBOL divisions for?

IDENTIFICATION, ENVIRONMENT, DATA, PROCEDURE. Do I always need all four? What goes in each?

IDENTIFICATION = program name.
ENVIRONMENT = files / ASSIGN (and some config).
DATA = your fields, FD, copybooks.
PROCEDURE = the actual code.

You will see all four in most batch programs. Some short programs look sparse in ENVIRONMENT if they barely touch files.

PROGRAM-ID under IDENTIFICATION is the one beginners forget, then the compile complains immediately.