> I never understood how to capitalize headlines correctly. Can someone eli5 ?:D

On HN, copy/paste is usually a safe bet (with a few exceptions): https://news.ycombinator.com/newsguidelines.html

If you mean in general, Wikipedia sums it up pretty well: https://en.wikipedia.org/wiki/Title_case

> On HN, copy/paste is usually a safe bet

Also note that HN automatically applies the capitalization rules to submitted headlines. So you don’t really need to do any changes to the capitalization yourself when you submit.

And for understanding how the rules work, I agree that Wikipedia article is good.

In English, the most common convention is to capitalize every word, or every word except small ones like articles and prepositions (the, of, for).

In US English. Not in the UK.

That's region-specific. Certainly not a feature of the language.

It's a feature of the language dialect.

Generally, capitalize longer words. But this really depends on the style book you choose to follow (MLA, APA, CMOS). See: https://en.wikipedia.org/wiki/Title_case

See also this nice title-case converter web app: https://titlecaseconverter.com/

Like a big chunk of the language, English capitalisation is nonsensical and descriptivist. Different organisations have different rules just like different audiences have different expectations, and there is no single way to capitalise words in titles.

I'm with the parent comment on this one: for this particular headline it makes sense to lowercase "teams", since the HN audience will tend to correlate the uppercase version with the incorrect meaning of the headline.