>Search for X and Y. This will return only results related to both X and Y. Note: It doesn’t really make much difference for regular searches, as Google defaults to “AND” anyway. But it’s very useful when paired with other operators.
The author must be using a different google than me. It's been many, many years since google functioned as an AND search. It very frequently decides to drop one or more words from my search if there is a low number of results, it's extremely annoying. Once you could force the old behaviour with +<term>, and then later with quoting ("term"). Both of those now also tend to drop search terms for me.
If anyone has an actually reliable way to get a real AND search out of google, I'm all ears.