Text Statistics
Words, sentences, paragraphs, average word length, longest sentence and unique-word ratio.
Worked example
Unique word ratio below about 40% in a 500-word article usually means repetition rather than concision — the same few nouns doing all the work. Above 60% is normal for edited prose; above 70% is typical of lists and data.
Word count is the number every editor asks for and the least interesting one. The secondary figures — average word length, longest sentence, unique word ratio — are what actually indicate whether a passage reads well.
Reading the numbers
Average English word length sits near 4.7 characters. Sustained averages above 6 mean heavy nominalisation: long abstract nouns instead of verbs. A longest sentence above 35 words is worth splitting regardless of what the total count says.
Sentence and paragraph detection
Sentences are split on terminal punctuation, which miscounts abbreviations such as "Dr." and decimals such as "3.5". Paragraphs are split on blank lines, so a document with soft returns throughout will report one paragraph. Both are heuristics, not parsing.
Counting rules differ
Microsoft Word counts "don't" as one word; some CMSs count hyphenated compounds as two. If you are matching a client's number, ask which tool they are using rather than arguing about the arithmetic.