Each module is for a specific task with parameters can be changed.
Community exists for adding their own modules and share.
It is kind of a command center.
These can be used inside a playbook or in ad-hoc commands.

Module Docs:
Ansible has local access to documentation, no need of internet.
ansible-doc -l –> To list all modules.
ansible-doc module_name –> specific module help
ansible-doc -s module_name –> for playbook snippet/example
3 kinds of modules:
core: modules supported by ansible themselves
extras: by communities
deprecated: when a new modules if going to replace it, they are kept on hold to delete later.
Some module categories:
Manage Servers
Deploy Configurations
Configure network equipment — like cisco
Manage databases and tables
Deploy load-balancer configurations