Hinter vs. hinten
The German words hinter and hinten can both be translated as behind or at the back, but they are used very differently. The core difference is that hinter is a preposition that needs an object, while hinten is an adverb that describes a location on its own.
Hinter
A1This word is a preposition meaning behind. It must be followed by a noun that specifies what something is behind. It answers the questions Wo? (Where? - with the dative case) and Wohin? (Where to? - with the accusative case).
Der Hund schläft hinter dem Sofa.
(The dog is sleeping behind the sofa.)
Er lief schnell hinter das Haus.
(He ran quickly behind the house.)
Was versteckst du hinter deinem Rücken?
(What are you hiding behind your back?)
Ich parke mein Auto immer hinter deinem.
(I always park my car behind yours.)
Die Kinder spielen hinter dem Baum.
(The children are playing behind the tree.)
Hinten
A1This word is an adverb of place, meaning at the back, in the rear, or in the back. It stands alone and does not take an object. It answers the question Wo? (Where?).
Im Bus sitze ich am liebsten hinten.
(On the bus, I prefer to sit at the back.)
Das Kleingedruckte steht ganz hinten auf der Seite.
(The fine print is at the very back of the page.)
Mein Garten ist hinten viel größer.
(My garden is much bigger at the back.)
Bitte steigen Sie hinten ein.
(Please get in at the back.)
Die Toilette ist den Flur runter und dann hinten links.
(The toilet is down the hall and then at the back on the left.)
Summary
The key takeaway is function. Use hinter (preposition) when you want to say something is behind something else. You always need to state that something else. Use hinten (adverb) when you simply want to state a general location: at the back or in the back, without specifying what it is behind.