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What is the difference between join and merge in Pandas?

Updated May 17, 2026

Short answer

merge is key-based; join is index-based by default.

Deep explanation

merge is flexible SQL-like joining on columns or indexes, while join is a convenience method primarily for index-based combining. merge is more general.

Real-world example

Joining customer data with transaction records.

Common mistakes

  • Using join without understanding index alignment.

Follow-up questions

  • Which is more commonly used?
  • Can join use columns?

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