Model tiers (Haiku, Sonnet, Opus).

Claude comes in three tiers, and the names tell you the tradeoff. Haiku is the cheapest and fastest. Sonnet is the solid everyday model. Opus is the most capable, built for complex or coding-heavy work.

Here's how I actually use them. I pretty much never touch Haiku, it's mostly for big automations running at scale. Sonnet is my default to save Tokens. I sit in Opus for anything hard, because the difference is night and day.

One thing that trips people up: ignore the version numbers. They change constantly. The tier names stay, so anchor on those.