Use 'drop in' to describe a casual, unplanned visit to someone's place.

Spontaneous Visit

'Drop in' suggests a quick visit, not an extended stay.

Short Duration

'Drop in' is informal, so it's not usually used in professional settings.

When 'drop in' refers to decrease, context clues like 'temperature' or 'price' are often present.

Use 'drop in' to express a quick or unexpected decrease.

Use 'drop in' when you're describing joining an activity without needing to register first.

'Drop in' for an activity implies casual or optional participation.

A 'drop in' center offers various types of help and information, often informally.

No appointment is needed to 'drop in' at most centers or clinics.

In poker, 'drop in' means choosing not to continue in a round of betting.