When you’re talking about two things that go together, use the adjective both. If you put on both of your boots, you are wearing the left one and the right one.
When you use the word both, you’re always talking about two of something. If you say you’re having dinner with both of your brothers this weekend, it means you have two brothers. When you call both of your dogs to come inside, it’s clear you’ve got two dogs. There are a few theories about the origin of both, including the Old English word begen, “both,” and the the Old Norse baðir, also “both.”
(used with count nouns) two considered together; the two“both girls are pretty”
quantifier; used with either mass nouns or plural count nouns to indicate an unspecified number or quantity