Computers do not store characters directly. Instead, they store bytes, which are sequences of numbers. Encoding converts a string into bytes, while decoding converts bytes back into a string.

Python provides the encode() and decode() methods for converting between strings and bytes. The most commonly used encoding standard is UTF-8, which supports characters from almost every language.

Encoding and decoding are essential when reading and writing files, sending data over networks, communicating with APIs, and storing text in binary formats.

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Syntax #

string.encode()

or

string.encode("utf-8")

or

bytes_object.decode()

or

bytes_object.decode("utf-8")

Components #

Component	Description
string	The Unicode string to encode.
encode()	Converts a string into bytes.
bytes_object	The bytes object to decode.
decode()	Converts bytes back into a string.
"utf-8"	The encoding format used for conversion.

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Example 1: Encoding a String #

main.py

text = "Python"

print(text.encode())

Output #

b'Python'

Explanation #

• encode() converts the string into bytes.
• The prefix b indicates a bytes object.
• UTF-8 encoding is used by default.

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Example 2: Encoding with UTF-8 #

main.py

text = "Hello"

print(text.encode("utf-8"))

Output #

b'Hello'

Explanation #

• "utf-8" is specified explicitly.
• The result is the same because UTF-8 is the default encoding.
• A bytes object is returned.

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Example 3: Encoding Unicode Text #

main.py

text = "नमस्ते"

print(text.encode("utf-8"))

Output #

b'\xe0\xa4\xa8\xe0\xa4\xae\xe0\xa4\xb8\xe0\xa5\x8d\xe0\xa4\xa4\xe0\xa5\x87'

Explanation #

• Unicode characters are converted into UTF-8 bytes.
• Each character may occupy multiple bytes.
• The result is a bytes object.

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Example 4: Decoding Bytes #

main.py

data = b'Python'

print(data.decode())

Output #

Python

Explanation #

• decode() converts bytes back into a string.
• UTF-8 decoding is used by default.
• The returned value is a string.

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Example 5: User Input #

main.py

text = input("Enter text: ")

encoded = text.encode()

print(encoded)

Sample Input #

Hello

Output #

b'Hello'

Explanation #

• The user enters a string.
• encode() converts the string into bytes.
• The encoded bytes are displayed.

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Example 6: Encoding and Decoding Together #

main.py

text = "Python"

encoded = text.encode()

decoded = encoded.decode()

print(decoded)

Output #

Python

Explanation #

• The string is first encoded into bytes.
• The bytes are then decoded back into a string.
• The original text is restored.

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Example 7: Checking the Data Type After Encoding #

main.py

text = "Python"

result = text.encode()

print(type(result))

Output #

<class 'bytes'>

Explanation #

• encode() returns a bytes object.
• The data type is bytes.
• It is different from str.

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Example 8: Checking the Data Type After Decoding #

main.py

data = b'Python'

result = data.decode()

print(type(result))

Output #

<class 'str'>

Explanation #

• decode() converts bytes into a string.
• The returned value is of type str.
• The original bytes remain unchanged.

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Example 9: Encoding an Emoji #

main.py

text = "😊"

print(text.encode("utf-8"))

Output #

b'\xf0\x9f\x98\x8a'

Explanation #

• Emojis are Unicode characters.
• UTF-8 represents them using multiple bytes.
• The encoded value is displayed as hexadecimal escape sequences.

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Example 10: Encoding Mixed Languages #

main.py

text = "Hello नमस्ते"

encoded = text.encode("utf-8")

print(encoded)

Output #

b'Hello \xe0\xa4\xa8\xe0\xa4\xae\xe0\xa4\xb8\xe0\xa5\x8d\xe0\xa4\xa4\xe0\xa5\x87'

Explanation #

• The English and Hindi text are encoded together.
• UTF-8 supports characters from multiple languages.
• The result is a single bytes object.

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Common Mistakes #

1. Calling decode() on a String #

Incorrect

text = "Python"

print(text.decode())

Output #

AttributeError: 'str' object has no attribute 'decode'

Reason

decode() is a method of bytes, not str.

Correct

data = b'Python'

print(data.decode())

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2. Calling encode() on Bytes #

Incorrect

data = b'Python'

print(data.encode())

Output #

AttributeError: 'bytes' object has no attribute 'encode'

Reason

encode() is a method of strings, not bytes.

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3. Assuming encode() Modifies the Original String #

Incorrect

text = "Python"

text.encode()

print(type(text))

Output #

<class 'str'>

Reason

encode() returns a new bytes object.
The original string remains unchanged.

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4. Assuming Encoded Data Is Still a String #

Incorrect

text = "Python"

encoded = text.encode()

print(type(encoded))

Incorrect Expectation #

<class 'str'>

Actual Output #

<class 'bytes'>

Reason

Encoding converts a string into a bytes object.

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Best Practices #

• Use UTF-8 for most encoding and decoding operations.
• Encode text before writing binary data or sending data over a network.
• Decode bytes immediately after reading binary text data.
• Remember that strings and bytes are different data types.
• Store encoded and decoded values in separate variables for better readability.

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Key Points to Remember #

• Encoding converts a string into bytes.
• Decoding converts bytes back into a string.
• encode() is a method of str.
• decode() is a method of bytes.
• UTF-8 is the default and most widely used encoding.
• encode() returns a value of type bytes.
• decode() returns a value of type str.

Congratulations! You have now completed Chapter 4: Strings. The next chapter will introduce Lists, Python’s first built-in mutable collection type.