Words, characters and reading time, live, and why different tools sometimes give slightly different numbers for the same text.

You wrote something with a word limit (a bio, a summary, a school assignment) and need to confirm how many words you're at. Opening all of Word just for that is overkill, and pasting the text into a search engine doesn't always give a reliable number.
The counter updates five numbers live as you type: words, characters with spaces, characters without spaces, paragraphs, and an estimated reading time.
There's no single universal standard for what counts as "a word": some tools treat a hyphen as a word separator, others don't; some ignore standalone numbers, others count them. So it's normal to see a small difference (a few words) between Word, Google Docs, and a tool like this one for the same text. If a word limit is strict, the safest bet is to measure with whatever tool the person reviewing it will use.
It divides the word count by 200, an average silent-reading speed, and rounds to the nearest minute (with a one-minute floor), a quick way to estimate how long a text will take someone to read before publishing it.
Nothing you type is saved or sent anywhere: everything is calculated in your browser. This and other text tools are free at Giga Useful Tools.