wenn clauses

wenn covers both if and when, in the sense of a condition or something that happens regularly. Structurally it is familiar territory: like weil and dass, it sends the conjugated verb to the end of its own clause.

wenn · subject · … · conjugated verb (end). Exactly the weil pattern.

• Ich bleibe zu Hause, wenn es regnet.

  I stay at home when it rains.

• Ich rufe dich an, wenn ich zu Hause bin.

  I will call you when I am home.

• Ich trinke Kaffee, wenn ich müde bin.

  I drink coffee when I am tired.

Now the genuinely new part, and it is a neat extension of something you already know. The wenn-clause can come first — and when it does, it occupies position 1 of the whole sentence. So the main clause verb still has to be second, which means it lands immediately after the comma.

• Wenn es regnet, bleibe ich zu Hause.

  When it rains, I stay at home.

  [Wenn es regnet] = position 1 · bleibe = position 2

• Wenn ich Zeit habe, spiele ich Videospiele.

  When I have time, I play video games.

• Wenn ich müde bin, trinke ich Kaffee.

  When I am tired, I drink coffee.

Verb — comma — verb. When a wenn-clause comes first, the two verbs end up either side of the comma.

That "verb, comma, verb" shape is a reliable thing to check your own sentences against. Wenn ich Zeit habe, spiele ich… — if you have written …habe, ich spiele, the verb has slipped to position 3.

Both orders mean the same thing. Putting the wenn-clause first gives the condition slightly more emphasis, which is why it is so common in speech.

German does distinguish wenn from als (for a single event in the past) and falls (for a more hypothetical if). Those belong to a later lesson — at this level, wenn handles conditions and repeated situations perfectly well.