die Plattform
platform
An elevated, flat structure, for example a train platform, a stage, or a loading ramp.
Der Zug nach Hamburg fährt heute von Plattform 7 ab.
The train to Hamburg departs from platform 7 today.

platform
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platform
An elevated, flat structure, for example a train platform, a stage, or a loading ramp.
Der Zug nach Hamburg fährt heute von Plattform 7 ab.
The train to Hamburg departs from platform 7 today.

For all meanings of 'Plattform' (platform), the preposition 'auf' (on) is almost always used to describe a location or a basis.
Wir warten auf Plattform 3 auf den Zug.
We're waiting for the train on platform 3.
You can recognize the digital meaning from words like 'online', 'digital', 'sozial' (social), 'Internet', or 'App'. Here it refers to a technical basis for software or communication.
Facebook ist eine soziale Plattform, um mit Menschen in Kontakt zu bleiben.
Facebook is a social platform for staying in contact with people.
In the figurative sense of 'Forum' (forum), 'Plattform' (platform) is often used with the verbs 'bieten' (to offer/provide) or 'schaffen' (to create). The idea is to create an opportunity for exchange or discussion.
Die Tagung bietet eine ideale Plattform für den wissenschaftlichen Austausch.
The conference provides an ideal platform for academic exchange.
The meaning 'Bohranlage' (drilling rig) becomes clear through the context of the sea, oil, or gas. The word 'Bohrplattform' (drilling platform) is often used.
Die Arbeiter fliegen mit dem Helikopter zur Plattform im Meer.
The workers fly by helicopter to the platform at sea.
website
'die Website' and 'die Plattform' can both occur on the internet, but they do not mean the same thing. A website is a specific internet presence under one address, for example with information, images, and contact pages. A platform is more of a technical or organizational basis on which people can do something: sell, learn, share videos, or exchange ideas. Learners may confuse the words because many platforms are also visible as websites. A website displays content; a platform often enables actions and exchange.

Nach der Anmeldung kann Lena auf der Plattform mit anderen Teilnehmern chatten.
After registering, Lena can chat with other participants on the platform.
Für den Kurs lädt die Lehrerin die Aufgaben auf die Website der Schule.
For the course, the teacher uploads the assignments to the school's website.