The most common letter in the English alphabet, by typical usage frequency, is E.
E is the fifth letter of the Latin alphabet and the second vowel in the modern English alphabet. In ordinary English prose, it generally appears more often than any other letter, with widely cited analyses placing its frequency at about 12.7 percent of letters in a representative body of text.
Its high frequency comes partly from common grammatical and lexical patterns. E appears in extremely common words such as the, be, he, we, were, and have, and it occurs in endings such as -ed and -es. Its importance is also reflected in cryptography: frequency analysis often begins by testing the most common symbol as a possible E.
The exact ranking is not universal. Results change depending on whether researchers count books, newspapers, dictionaries, word lists, technical writing, or word initials. T can become especially prominent in some texts, while A may lead among word beginnings. The quiz answer E refers to overall letter frequency in representative English writing, not the most common first letter or the most common letter in every individual passage.