IaC Concepts & Terraform's Purpose

IaC is the practice of managing and provisioning infrastructure through machine-readable definition files rather than manual console clicks or interactive one-off scripts. The files become the authoritative description of what infrastructure should exist.

Manual console provisioning produces no reusable, reviewable artifact, is error-prone, hard to reproduce, and undocumented. IaC replaces those ad-hoc clicks with versioned files that can be reviewed, diffed, and reapplied consistently.

In a declarative model you describe the desired end state of infrastructure, and the engine computes how to reach it. You do not write the ordered steps; Terraform determines the necessary create, update, and destroy actions from the difference between desired state and current state.

Imperative IaC specifies the explicit ordered steps to perform (do A, then B, then C). Declarative IaC specifies only the goal state and lets the tool figure out the steps. Terraform is declarative; many shell-script or procedural approaches are imperative.

Because you only describe the end state, the same configuration can be reapplied safely regardless of current state, and the tool computes the minimal changes. You avoid writing and maintaining brittle step-by-step procedures and avoid having to know the existing state in advance.

Configuration drift is the divergence between the real running infrastructure and the codified desired state (or recorded state) — typically caused by out-of-band manual changes. IaC tools can detect drift and reconcile the real world back to the declared configuration.