Latin Small Letter E
The most frequently used letter in the English language, accounting for roughly 12–13 % of all characters in typical corpora — a dominance that has made it a cornerstone of frequency analysis in classical cryptography. Lowercase 'e' sits at ASCII code point 101 (0x65), 32 above its uppercase counterpart 'E' at 69 (0x45), maintaining the single-bit case offset (bit 5) shared by all ASCII A–Z / a–z pairs. It also serves as one of the six hexadecimal letter-digits, representing the value 14.
Technical Details
Code Example
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// Scientific notation and Euler's number#include <math.h>double sci = 1.5e6; // 1,500,000double euler = M_E; // 2.71828...
Common Usage
Hexadecimal digit: Lowercase 'e' represents 14 in hex notation and appears throughout SHA digests, MAC addresses, UUIDs, and CSS color values. It surfaces frequently in hex dumps simply because it is a valid digit in many byte values (e.g., 0xEF, 0xFE).
Scientific and exponential notation: In most mainstream programming languages and data formats, 'e' serves as the exponent separator in floating-point literals — 1.5e3 means 1500, 2.998e8 approximates the speed of light. This convention traces back to early Fortran and persists in JSON, Python, C, JavaScript, and many others.
Frequency analysis anchor: Because 'e' is by far the most common letter in English, it is typically the first target in frequency-based ciphertext attacks. Its statistical dominance as a cryptanalytic tool is documented as early as al-Kindi's 9th-century treatise on deciphering encrypted messages.
Diacritical variants: Few letters rival the breadth of 'e' in accented forms — è (grave), é (acute), ê (circumflex), ë (diaeresis), ě (caron), ę (ogonek), and ē (macron) appear across French, Spanish, Czech, Polish, Māori, and many other Latin-script orthographies.
Hexadecimal digit: Lowercase 'e' represents 14 in hex notation and appears throughout SHA digests, MAC addresses, UUIDs, and CSS color values. It surfaces frequently in hex dumps simply because it is a valid digit in many byte values (e.g., 0xEF, 0xFE).
Scientific and exponential notation: In most mainstream programming languages and data formats, 'e' serves as the exponent separator in floating-point literals — 1.5e3 means 1500, 2.998e8 approximates the speed of light. This convention traces back to early Fortran and persists in JSON, Python, C, JavaScript, and many others.
Frequency analysis anchor: Because 'e' is by far the most common letter in English, it is typically the first target in frequency-based ciphertext attacks. Its statistical dominance as a cryptanalytic tool is documented as early as al-Kindi's 9th-century treatise on deciphering encrypted messages.
Diacritical variants: Few letters rival the breadth of 'e' in accented forms — è (grave), é (acute), ê (circumflex), ë (diaeresis), ě (caron), ę (ogonek), and ē (macron) appear across French, Spanish, Czech, Polish, Māori, and many other Latin-script orthographies.