Why the word "both" is considered as a determiner (According to the Cambridge and the Collins dictionary)? Example sentence: Both kids walked a minute ago.
Isn't it a quantifier? Also if yes then could you please tell me how to know when a word acts like a quantifier and when it acts like a determiner?
Quantifiers are determiners (though not all determiners are quantifiers).
There are many different types of determiner. One way of classifying them is by position: there are predeterminers ("twice", "double", "half", "all", "both"); central determiners ("the", "a", "this", "my", "your"); and postdeterminers ("one", "two", "three", "several", "many", "few").
Most quantifiers are postdeterminers, i.e. they come after an article or possessive adjective (where present): "the many people", "his few friends".
"All" and "both" are predeterminers, i.e. they come before an article or possessive adjective (where present): "all the boys", "both his sisters".
