Ansible's `replace` module is used for deploying applications, managing systems, and enforcing configuration across remote machines. It uses a simple, agentless push model from a central control node and defines tasks in YAML with reusable modules. Modules are the building blocks of Ansible tasks — they handle everything from installing software and managing users to editing files and configuring networks. They're idempotent, meaning they can run repeatedly without causing unexpected changes, which helps keep systems consistent and reliable. The `replace` module is particularly useful for updating configuration files to change database connection strings, update port configurations or API keys, or modify file paths across multiple servers. It supports regular expressions, backup options, and controlled replacements using `before` and `after` keywords, offering flexibility and safety, especially in production. However, it may not be the best fit when dealing with complex patterns or when you need to pass specific variables or external data into a file, as the `template` module is more suitable for those use cases. Additionally, Spacelift's ecosystem can help manage and orchestrate Ansible playbooks, combining IaC with configuration management, and providing insights into what ran and where.