Byte string creation

Provides a way to encode text as raw bytes for low-level operations.

File handling: writing binary files with open(..., 'wb'); Networking: sending raw bytes over a socket; Cryptography: hashing binary data with hashlib

Python standard library, networking scripts, file handling, data serialization.

b'payload'

b'...'

The ASCII or UTF-8 string to be encoded as bytes (e.g., 'hello', file path, JSON payload).

• open with 'wb' mode
• socket.send
• hashlib.sha256
• struct.pack

• Using bytes() constructor with a string and encoding
• e.g.
• bytes('hello'
• 'utf-8')
• or using bytearray.

Confusing b'hello' with regular string 'hello', leading to type errors when concatenating or forgetting to decode before printing.

Regular string literals ('hello') vs bytes literals (b'hello'); the former is Unicode text, the latter raw bytes. Also contrast with bytearray(b'hello') for mutable byte sequences.

Coming from languages where strings are bytes by default (e.g., C), you may forget that Python 3 distinguishes str and bytes, causing encoding/decoding errors.

• bytearray construction
• memoryview
• struct.pack
• base64 encoding

Bytes literals only accept ASCII characters unless you use escape sequences (e.g., b'\\xnn') or encode via bytes() with an explicit encoding; they are immutable.

Makes intent explicit that the data is binary, preventing accidental Unicode encoding issues.

Think of the 'b' as 'binary' prefix.

Bytes literals produce immutable bytes objects; for mutable byte sequences use bytearray().

bytes('hello', 'utf-8')