The euro is represented in Unicode as U+20AC € EURO SIGN. In modern computer systems and mobile phones, this is the only codepoint used. When first introduced, however, work to retrofit the symbol into crowded pre-existing character set standards and vendor-specific schemas presented challenges that were not fully resolved until widespread adoption of Unicode.
Initially, different vendors assigned the euro sign to different code positions in their historic encoding schemes. This led to many initial problems displaying the euro sign consistently in computer applications, depending on access method. While displaying the euro sign was no problem as long as only one system was used (provided an up-to-date computer font with the proper glyph was available), but mixed setups often produced errors. Initially, Apple, Microsoft and Unix systems chose a different code point to represent a euro symbol: thus a user of one system might have seen a euro symbol whereas (when the file was transferred) another would see a different symbol or nothing at all. In such situations character set conversions had to be made, often introducing conversion errors such as a question mark ⟨?⟩ being displayed instead of a euro sign.

Initially, some mobile phone companies issued an interim software update for their special SMS character set, replacing the less-frequent Japanese yen sign with the euro sign. Subsequent mobile phones have both currency signs.
Depending on keyboard layout and the operating system, there is a variety of ways to enter the symbol. The symbol is engraved on most keyboards used in Europe. (For entry methods in other territories, please refer to local sources or the article Unicode input.)

Placement of the sign varies. Countries have generally continued the style used for their former currencies. In those countries where previous convention was to place the currency sign before the figure, the euro sign is placed in the same position (e.g., €3.50). In those countries where the amount preceded the national currency sign, the euro sign is again placed in that relative position (e.g., 3,50 €).

In English the euro sign – like the dollar sign ⟨$⟩ and the pound sign ⟨£⟩ – is usually placed before the figure, unspaced, the reverse of usage in many other European languages. When written out, "euro" is placed after the value in lower case; the plural is used for two or more units, and euro cents are separated with a full-stop, not a comma as in many countries (e.g., €1.50, 14 euros). The European Union's Interinstitutional Style Guide (for EU staff) states that the euro sign should be placed in front of the amount without any space in English, but after the amount in most other languages.

Prices of items costing less than one euro are often written using a local abbreviation like ct. (particularly in Spain and Lithuania); c. (Ireland); Λ (Greece (lambda)); snt. or written -, without any symbol (Finland). For example, 10 cents may be written as 10 ct., 10c., 10Λ, 10 snt. or -,10, depending on location. The US style ¢ is rarely seen in formal contexts. In all cases, prices may be written as decimals, e.g. €0.07 or 0,07 €, according to national conventions. .

• Currency symbol § List of currency symbols currently in use