What 다 means
Context decides its job. Inside a word, 다 just supplies the sound da. The ending -다 marks dictionary forms of verbs and plain written statements. A particle 다, shortened from 다가, can follow a place or means.
Hangul, the Korean alphabet, was created on purpose so Korean could be written simply, not only through Chinese characters. It is first recorded in 1443 and got an explanatory book in 1446.
Questions people ask
1Is 다 rude in a text?
Not automatically. Plain -다 is less polite than -어요, but a longer ending must be judged as a whole.
How to type 다
다\B2E4Codes and encoding1 code points
A visible symbol can contain several code points. JS .length counts UTF-16 units; UTF-8 counts bytes.

