The imperative is a form that expresses a command.

Depending on which verb group the verb belongs to, the imperative can be formed by using either the infinitive form or the stem of the verb. If the present tense ending of the verb is –ar, then the infinitive form is used. If the ending is either –er or –r, the ending is removed and the stem of the verb is used as the imperative instead.

Group I: Stanna här! (stann/ar -> infinitive)

Group II: Rök inte! (rök/er -> verb stem)

Group III : Tro på mig! (tro/r -> verb stem)

Group IV: Ät bättre! (ät/er -> verb stem)

The qualifier (e.g. negation) comes right after the verb in the imperative form. If the verb stem ends with two m-letters, the imperative form takes only one: 

glömma, (infinitive), glömmer (present) -> glöm (imperative)

Glöm inte att ta din medicin!

Don’t forget to take your medicine!

The imperative forms otherwise have the same form regardless of whether one or more people are being commanded, but with reflexive verbs (i.e. verbs with the reflexive pronoun sig) the pronoun dig is used when commanding one person, and er when commanding several people:

Lägg dig! = Go to sleep! (to one person)

Lägg er!  = Go to sleep! (to multiple people)