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+# Rotational Cipher
+
+Welcome to Rotational Cipher on Exercism's Python Track.
+If you need help running the tests or submitting your code, check out `HELP.md`.
+
+## Instructions
+
+Create an implementation of the rotational cipher, also sometimes called the Caesar cipher.
+
+The Caesar cipher is a simple shift cipher that relies on transposing all the letters in the alphabet using an integer key between `0` and `26`.
+Using a key of `0` or `26` will always yield the same output due to modular arithmetic.
+The letter is shifted for as many values as the value of the key.
+
+The general notation for rotational ciphers is `ROT + <key>`.
+The most commonly used rotational cipher is `ROT13`.
+
+A `ROT13` on the Latin alphabet would be as follows:
+
+```text
+Plain:  abcdefghijklmnopqrstuvwxyz
+Cipher: nopqrstuvwxyzabcdefghijklm
+```
+
+It is stronger than the Atbash cipher because it has 27 possible keys, and 25 usable keys.
+
+Ciphertext is written out in the same formatting as the input including spaces and punctuation.
+
+## Examples
+
+- ROT5 `omg` gives `trl`
+- ROT0 `c` gives `c`
+- ROT26 `Cool` gives `Cool`
+- ROT13 `The quick brown fox jumps over the lazy dog.` gives `Gur dhvpx oebja sbk whzcf bire gur ynml qbt.`
+- ROT13 `Gur dhvpx oebja sbk whzcf bire gur ynml qbt.` gives `The quick brown fox jumps over the lazy dog.`
+
+## Source
+
+### Created by
+
+- @krapes
+
+### Contributed to by
+
+- @akashsara
+- @behrtam
+- @cmccandless
+- @Dog
+- @dotrungkien
+- @ikhadykin
+- @lekum
+- @N-Parsons
+- @tqa236
+
+### Based on
+
+Wikipedia - https://en.wikipedia.org/wiki/Caesar_cipher