In the later and more flowing New Roman Cursive, ligatures of all kinds were extremely common; figures 2 and 3 from the middle of 4th century are examples of how the et-ligature could look in this script.

[11] The modern italic type ampersand is a kind of "et" ligature that goes back to the cursive scripts developed during the Renaissance.

Since the ampersand's roots go back to Roman times, many languages that use a variation of the Latin alphabet make use of it.

[13] In her 1859 novel Adam Bede, George Eliot refers to this when she makes Jacob Storey say: "He thought it [Z] had only been put to finish off th' alphabet like; though ampusand would ha' done as well, for what he could see.

"[14] The popular nursery rhyme Apple Pie ABC finishes with the lines "X, Y, Z, and ampersand, All wished for a piece in hand".

In everyday handwriting, the ampersand is sometimes simplified in design as a large lowercase epsilon Ɛ or a reversed numeral 3, superimposed by a vertical line.

[15] The plus sign + (itself based on an et-ligature[16]) is often informally used in place of an ampersand, sometimes with an added loop and resembling ɬ.

[citation needed] Other times it is a single stroke with a diagonal line connecting the bottom to the left side.

Ampersands are commonly seen in business names formed from a partnership of two or more people, such as Johnson & Johnson, Dolce & Gabbana, Marks & Spencer, and Tiffany & Co., as well as some abbreviations containing the word and, such as AT&T (American Telephone and Telegraph), A&P (supermarkets), P&O (originally "Peninsular and Oriental", shipping and logistics company), R&D (research and development), D&B (drum and bass), D&D (Dungeons & Dragons), R&B (rhythm and blues), B&B (bed and breakfast), and P&L (profit and loss).

Many languages with syntax derived from C, including C++, Perl,[23] and more differentiate between: In C, C++,[24] and Go,[25] a prefix & is a unary operator denoting the address in memory of the argument, e.g. &x, &func, &a[3].

[29] Ampersand is the string concatenation operator in many BASIC dialects, AppleScript, Lingo, HyperTalk, and FileMaker.

[citation needed] In some versions of BASIC, unary suffix & denotes a variable is of type long, or 32 bits in length.

[citation needed] The ampersand was occasionally used as a prefix to denote a hexadecimal number, such as &FF for decimal 255, for instance in BBC BASIC.

[31] Dyalog APL uses ampersand similarly to Unix shells, spawning a separate green thread upon application of a function.

[citation needed] In more recent years, the ampersand has made its way into the Haskell standard library, representing flipped function application: x & f means the same thing as f x.

This convention originated in the first WIN32 api, and is used in Windows Forms,[40] (but not WPF, which uses underscore _ for this purpose) and is also copied into many other toolkits on multiple operating systems.

Sometimes this causes problems similar to other programs that fail to sanitize markup from user input, for instance Navision databases have trouble if this character is in either "Text" or "Code" fields.