| Source | Format | Best for | |--------|--------|----------| | | 2,800 words (core) + 2,200 extension | Most efficient for learners | | COCA (Corpus of Contemporary American English) | 5,000 sorted by frequency | Real US English | | Oxford 5000 | 5,000 words (B1–C1 level) | British English & exams | | Anki shared decks | “5k English words with audio” | Spaced repetition |