What does 'run into someone' mean?

The main meaning: To encounter someone or something unexpectedly.

"I ran into my old teacher at the supermarket."
"You'll never guess who I ran into today."

Other meanings:

Run into problems/trouble: To encounter a difficulty. "The project ran into problems with the budget." This is very common in business English.

Run into a number: To reach a large amount. "The costs ran into thousands."

Crash into: Literally driving into something. "He ran into the back of my car."

Which is most common? The unexpected meeting meaning is very frequent in everyday conversation. The "encounter problems" meaning is very common in business contexts.

• "I bumped into him" — British English, same meaning (accidental meeting)
• "I came across him" — slightly more formal

Tags: phrasal verbs, multiple meanings, meetings, everyday English