I’m not sure if I assumed it or someone taught me, but I always thought seraphim and cherubim were two special classes of angels. Though seraphim and cherubim aren’t mentioned often in the Bible (2 and 69 verses respectively), angels make a much more frequent appearance, in some 290 places.
In none of those passages does the Bible call angels seraphim or cherubim. (The dictionary labels all three as “celestial beings.”) Although seraphim and cherubim have wings, no verses say that angels do. The Bible never says angels fly, though there are some hints they are occasionally airborne, but as supernatural beings, they don’t need wings to go vertical.
Angels are mentioned more times in the New Testament (182 times) than in the Old (108 times), with Revelation giving them the most coverage (77 times), followed by Luke (24 times) and Acts (22 times). We don’t know if angels have genders or not, but one verse (Judges 13:21) implies that particular angel is masculine, so I refer to angels as “him” rather then “it.”
While we see seraphim as worshiping God and cherubim as hanging out with God in heaven and attesting to his glory, angels serve as God’s messengers to us. They show up unexpectedly, suddenly appearing and then disappearing. Apparently either their arrival or their form is frightening, because they often say, “Do not be afraid.”
If an angel ever visited me, I wonder if I’d shrink back in fear. I’d like to say I wouldn’t, but I suspect I would. Regardless of how I react, I will want to listen carefully to what the angel tells me, receiving it as a word from God.