unterstützen
to support
To help someone, often through financial, material, or practical assistance.
Meine Eltern unterstützen mich während des Studiums finanziell.
My parents support me financially during my studies.

to support
Loading your saved state.
to support
To help someone, often through financial, material, or practical assistance.
Meine Eltern unterstützen mich während des Studiums finanziell.
My parents support me financially during my studies.

'Unterstützen' (to support) is an inseparable verb. The prefix 'unter-' remains firmly attached to the verb 'stützen' (to support/brace) in all sentence forms and tenses.
Sie unterstützt ihn bei seiner Arbeit.
She supports him in his work.
The verb 'unterstützen' (to support) always needs an accusative object. You ask 'Wen oder was unterstützt du?' (Whom or what do you support?). The person or thing receiving help is in the accusative.
Die Organisation unterstützt arme Familien mit Lebensmitteln.
The organization supports poor families with food.
To describe the type of help more precisely, 'unterstützen' (to support) is often combined with adverbs. Common examples are 'finanziell unterstützen' (to support financially), 'moralisch unterstützen' (to support morally), or 'tatkräftig unterstützen' (to give active support).
Seine Freunde haben ihn nach dem Unfall vor allem moralisch unterstützt.
After the accident, his friends supported him mainly morally.
When it is about backing an idea, the objects are often abstract. Typical combinations are 'einen Plan unterstützen' (to support a plan), 'eine Initiative unterstützen' (to support an initiative), or 'einen Vorschlag unterstützen' (to support a proposal).
Alle Mitglieder des Teams unterstützten den neuen Vorschlag.
All members of the team supported the new proposal.
This meaning is typical in technical contexts. It is often used in the passive to describe the compatibility of software or devices.
Das neue Update wird von meinem alten Handy nicht mehr unterstützt.
The new update is no longer supported by my old phone.
behind
'hinter' and 'unterstützen' can both express that you stand by a person, opinion, or decision. This is especially true in the phrase 'hinter jemandem stehen' (to stand behind someone). This phrase emphasizes loyalty and backing: you do not leave the person on their own. 'unterstützen' is more direct and more general. It can mean that you actively advocate for someone, a plan, or an idea. When it is about attitude and trust, 'hinter jemandem stehen' sounds natural. When it is about concrete help or active support, 'unterstützen' fits better.

Viele Kolleginnen unterstützen den Vorschlag für flexiblere Arbeitszeiten.
Many colleagues support the proposal for more flexible working hours.
Das ganze Team steht hinter der neuen Trainerin.
The whole team stands behind the new coach.