Chef
In plain terms
A configuration-management tool using code-defined infrastructure.
Going deeper
Chef automates infrastructure setup with Ruby-based 'recipes' and 'cookbooks', enforcing desired system state. It's powerful for complex environments.
Under the hood
Agent-based pull model with strong programmability; steeper learning curve than Ansible.
Examples
Large-scale config management, infrastructure automation, compliance.
Think of it like...
Like a detailed cookbook each server follows to configure itself correctly.