A Caesar cipher is one of the earliest known and simplest ciphers. It is a type of substitution cipher in which each letter in the plaintext is 'shifted' a certain number of places down the alphabet. For example, with a shift of 1, A would be replaced by B, B would become C, and so on. (Practical Cryptography)
The method is named after Julius Caesar, who apparently used it to communicate with his generals. (Practical Cryptography)
Ravens are highly intelligent. Their intelligence is similar to that of chimpanzees. Being able to work complicated tasks and even mimic human speech. Though it's most common for them to mimic speech when raised in captivity, it's also known to happen in areas highly populated by humans. (Montanari, 2017)
A rhyming scheme is a pattern of rhyme. It is identified by the final word in a line of a stanza. (2018)
The rhyming scheme of The Raven is ABCBBB. That scheme is unique and creates the ominous tone of Edgar Allen Poe's poem.
A-weary B-lore C-tapping B-door B-door B-more (McDonald, 2019)