It relies on students knowledge about language and the world around them.
Example
Learners listen to a discussion between two unidentified speakers and must infer their relationship from what they hear.
In the classroom
The ability to infer meaning and situation correctly is an important skill, as in many cultures speakers avoid saying something directly by using implication. Ways to look at this include analysis of dialogue from films, learner implication - inference exchanges, listening tasks, using video and games, e.g. 'Find 10 ways to say Shut the door!'
Further links:
https://www.teachingenglish.org.uk/article/born-bread-buttered-london
https://www.teachingenglish.org.uk/article/planning-2
https://www.teachingenglish.org.uk/article/register-degrees-formality