What are Character Encodings?
Computers store everything as numbers. This includes text. But how do we represent letters, numbers, symbols, and characters from different languages as numbers? That’s where character encodings come in. A character encoding is a system that maps characters to numerical values, allowing computers to store and process text. Different encodings exist, each with its own strengths and limitations. Two common, historically significant encodings are ISO-8859-1 and UTF-8.
ISO-8859-1: A Single-Byte Encoding
ISO-8859-1 (also known as Latin-1) is an 8-bit character encoding. This means it uses a single byte (8 bits) to represent each character. Consequently, it can represent a maximum of 256 (28) different characters. It was designed primarily for Western European languages and covers characters like accented letters (é, à, ö), as well as basic punctuation and symbols.
The first 128 characters (0-127) in ISO-8859-1 are identical to the ASCII standard. This ensures that basic English text is displayed consistently. However, the remaining 128 characters are where it differs from ASCII and supports specific characters for languages like French, Spanish, German, and others.
Limitations: Because it’s limited to 256 characters, ISO-8859-1 cannot represent characters from many languages, including those that use Cyrillic, Greek, Arabic, Chinese, or Japanese. Trying to represent characters outside this range will result in garbled text or errors.
UTF-8: A Variable-Width Encoding
UTF-8 (Unicode Transformation Format – 8-bit) is a much more powerful and versatile character encoding. It’s the dominant encoding used on the web and in most modern systems. Unlike ISO-8859-1, UTF-8 is a variable-width encoding. This means it uses a different number of bytes to represent different characters.
- ASCII Characters: Characters in the ASCII range (0-127) are represented using a single byte, just like in ISO-8859-1. This ensures backward compatibility with existing ASCII files and systems.
- Other Characters: Characters outside the ASCII range are represented using two, three, or four bytes. This allows UTF-8 to represent a vastly larger range of characters – over 1.1 million Unicode code points, encompassing almost all writing systems in the world.
Benefits of UTF-8:
- Universal Character Support: It can represent virtually any character from any language.
- Backward Compatibility: It’s compatible with ASCII, meaning existing ASCII files can be treated as UTF-8 files without modification.
- Efficiency: For English text, UTF-8 uses the same amount of space as ASCII.
- Web Standard: It’s the preferred encoding for the web, ensuring consistent display of text across different platforms and browsers.
Key Differences Summarized
| Feature | ISO-8859-1 | UTF-8 |
|—————-|————|—————-|
| Encoding Type | Single-byte | Variable-width |
| Max Characters | 256 | 1,112,064+ |
| ASCII Support | Yes | Yes |
| Language Support | Western European | Universal |
| Web Standard | No | Yes |
Example in Python
Let’s illustrate the difference with a simple Python example:
# The copyright symbol © has Unicode code point U+00A9
copyright_symbol = chr(0xA9)
# Encode the symbol using UTF-8
utf8_encoded = copyright_symbol.encode('utf-8')
print(f"UTF-8 encoded: {utf8_encoded}")
# Encode the symbol using ISO-8859-1
iso8859_1_encoded = copyright_symbol.encode('iso-8859-1')
print(f"ISO-8859-1 encoded: {iso8859_1_encoded}")
This will produce the following output:
UTF-8 encoded: b'\xc2\xa9'
ISO-8859-1 encoded: b'\xa9'
Notice that UTF-8 requires two bytes (b’\xc2\xa9′) to represent the copyright symbol, while ISO-8859-1 can represent it with a single byte (b’\xa9′). If you tried to encode a character not present in the ISO-8859-1 character set with that encoding, you would get an error.
When to Use Which?
In almost all cases, UTF-8 is the preferred encoding. It offers the broadest character support, is the web standard, and provides backward compatibility with ASCII.
ISO-8859-1 might be used in legacy systems where compatibility with older software is essential and the text is limited to Western European languages. However, even in these cases, migrating to UTF-8 is generally recommended.