Conditions and Imperatives

The imperative in German is formed in two ways, depending on how polite you’re being.

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The polite imperative is extremely simple: add Sie after the infinitive.

Bitte machen Sie das Licht aus.
Please turn off the light.

Setzen Sie sich hin.
Sit down.

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To be honest, it’s not actually the infinitive. You’re cutting off the stem (turning machen into mach-) and then adding -en back on.

This produces the infinitive in all but one case: sein. Only with sein is it clear that you’re really adding something to the stem.

Seien Sie still!
Be quiet!

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The familiar imperative (using du) takes the form of the standard conjugation without the -st.

If it takes an umlaut in its du conjugation, remove the umlaut:

Du fährst zu langsam. Fahr schneller!
You’re driving too slow. Drive faster!

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There are three exceptions here: sein (becomes sei), wissen (becomes wisse), and werden (becomes werde). These last two are very rarely used.

Compared to that, the ihr form is a cinch: nothing changes at all from the normal form.

Bleibt hier.
Stay here.