Cherubim are mentioned several times in the Tanakh, or Old Testament, and are alluded to in the Book of Revelation. They are described as angelic creatures and in medieval Catholic theology are considered to be a certain rank of angels - one of the highest ranks, along with seraphim.
Descriptions in the Bible vary, but in general all describe cherubim as winged creatures combining human and animal features. In the book of Genesis cherubim are described as guarding the way to the Tree of Life armed with flaming swords (Gen 3:24). The book of Exodus states that cherubim are depicted in the Israelites' tabernacle. Cherubim are said to have been embroidered on the curtains of the tabernacle (Ex 26:1), and two sculpted cherubim are described as standing on the cover of the Ark of the covenant facing each other (Ex 25:18). The Ark of the covenant stood in the Holy of Holies, where the glory of God was said to reside; for this reason God is referred to in the Tanach as "God who dwells between the cherubim".
Cherub (כרוב) is a Hebrew word; its plural is cherubim (כרובים). In English it has become a synonym for angel. Because some English speakers are unfamiliar with Hebrew plural formation, the word cherubims is sometimes used as a plural, for example in the King James Bible. The etymology of the word cherub is very doubtful. Some scholars connect it with the Babylonian word karabu, meaning to be propitious or blessed. Others connect it with kirabu, the name of an Assyrian winged-bull god. Some scholars have also suggested tentatively that the Greek word gryphon might be derived from cherub.