Ampersand
& (Ampersand) is ASCII code point 38 (0x26), Unicode U+0026, and a printable punctuation character. It means "and" — a single glyph standing in for a three-letter word, which makes it one of the oldest surviving logographic shortcuts in the Latin alphabet. In C, C++, and their descendants, & does double duty: a single & is the bitwise AND operator and the address-of operator (&x yields a pointer), while && is logical AND with short-circuit evaluation. HTML and XML give it yet another life as the escape introducer — & renders a literal ampersand, < produces a less-than sign. This is where the character bites: if you inject user input into HTML without escaping ampersands, a string like "Tom & Jerry" might be interpreted as the start of a malformed character reference, and different browsers will guess differently about where the entity ends, producing garbled text or subtle XSS vectors that only surface in edge cases. The shape is a ligature of the Latin word "et" (meaning "and"). In many italic typefaces you can still see the E and t fused together — the glyph's ancestry hiding in plain sight. UTF-8 encodes it as a single byte 0x26. Unicode classifies it as Po (Punctuation, Other) with the name AMPERSAND. The rarely seen small ampersand ﹠ (U+FE60) and fullwidth ＆ (U+FF06) exist for CJK compatibility but almost never appear in Western text.
Technical Details
Code Example
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int x = 6, y = 3;int mask = x & y; // bitwise ANDint *p = &x; // address-of operator*p = mask;
Frequently Asked Questions
It comes from 'and per se and' — meaning 'the symbol & by itself means and.' It was once the 27th letter of the English alphabet. Kids reciting the alphabet would end with '...X, Y, Z, and per se and,' which slurred into 'ampersand' over centuries.
& is the bitwise AND — it compares individual bits (0b1010 & 0b1100 = 0b1000). && is the logical AND — it evaluates boolean expressions with short-circuit behavior (if the left side is false, the right side is never evaluated). Mixing them up causes subtle bugs.
Because & starts HTML character entities (like < > &). If you write 'Tom & Jerry' in HTML, the parser might try to interpret '& Jerry' as a malformed entity. & tells the parser 'this is a literal ampersand, not the start of an entity.'
At the end of a command, & runs it in the background (sleep 10 &). Between commands, && chains them with short-circuit logic (make && make install — only install if make succeeds). A single & between commands runs them in parallel, which is less common.