The most commonly used letter in the English alphabet is the letter "E." Studies analyzing English texts for letter frequency consistently show that "E" appears more often than any other letter. This predominance can be attributed to the common roots and word structures in the English language. For example, "E" is present in many frequently used words such as "the," "be," "he," "she," and "we." Its high frequency makes it integral to the formation of various grammatical constructs and overall communication. Thus, understanding this frequency is valuable for fields such as linguistics, cryptography, and data analysis.