X is the 24th letter of the modern English alphabet and the Latin alphabet which is the last letter.
X is a consonant
The letter X starts the fewest words in our language. You will rarely see a word that starts with X.
In mathematics, x represents an independent variable or unknown value.
In the Cartesian coordinate system the letter X is used to refer to the horizontal axis.
Also, the letter X is the Roman numeral for the number 10.