
anlehnen
to lean
To place or position something or oneself at an angle against a vertical surface for support.
Du kannst dein Fahrrad an die Hauswand anlehnen.
You can lean your bicycle against the wall of the house.
to lean / be based on
Loading your saved state.

to lean
To place or position something or oneself at an angle against a vertical surface for support.
Du kannst dein Fahrrad an die Hauswand anlehnen.
You can lean your bicycle against the wall of the house.

to be based on
To use a model or template as a guide when creating something; to be based on something.
Der Film lehnt sich in seiner Handlung eng an den Bestseller-Roman an.
The film's plot is closely based on the bestselling novel.
'Anlehnen' (to lean) is a separable verb. The prefix 'an-' stands at the end in a main clause. In subordinate clauses or in the infinitive with 'zu', the verb stays together.
Er lehnte sein Fahrrad an den Zaun an.
He leaned his bicycle against the fence.
The meaning can be recognized from the object. If it is about concrete, physical things (person, bicycle), the literal meaning is intended. With abstract things (film, theory, novel), the figurative meaning 'to be based on' is intended.
Bitte lehne die nasse Jacke nicht an die Tür an.
Please don't lean the wet jacket against the door.
In the literal meaning, the target that something is leaned against is always indicated with the preposition 'an' and the accusative. The verb can also be used reflexively ('sich anlehnen' — to lean oneself/lean back).
Er lehnte sich erschöpft an die Wand.
He leaned exhausted against the wall.
In the figurative meaning, the verb is always used reflexively and with the fixed preposition 'an' (+ accusative): 'sich an etwas anlehnen' (to be based on something). It means that something serves as a model or basis.
Das Design des neuen Autos lehnt sich stark an klassische Sportwagen an.
The design of the new car is strongly based on classic sports cars.
to be based
Basieren auf generally names the basis of a concept. Sich anlehnen an also means that something is based on a model, but it suggests a deliberate and recognizable orientation toward that model's design. Basieren is therefore usually suitable for data or findings, while anlehnen is more appropriate for an adopted model.

Das neue Kurskonzept lehnt sich an das bewährte Modell der Nachbarschule an.
The new course concept is modeled on the tried-and-tested approach used by the neighboring school.
Das neue Kurskonzept basiert auf den Ergebnissen der Teilnehmerbefragung.
The new course concept is based on the results of the participant survey.