Vocabulary banks can be recorded on cards, in the learners' notebooks or even online.
Example
Some learners carry a collection of small cards with them. Each card has a word on it, with a definition or translation, and an example.
In the classroom
Vocabulary banks can be kept by individual learners, incorporated into language portfolios, kept as a class resource in the form of wall charts, recorded in a permanent area on the whiteboard during a series of classes, or stored on a class blog.
Further links:
https://www.teachingenglish.org.uk/article/lexical-notebooks-or-vocabulary-cards
https://www.teachingenglish.org.uk/article/remembering-vocabulary
https://www.teachingenglish.org.uk/article/negotiated-objectives