Source: 📖 Effective Python item 3

Writing and reading binary data to and from files

Writing binary data to a file requires opening the file with writing binary wb mode:

with open('file.bin', 'wb') as f:
	f.write(...)

Reading binary data from a file requires opening the file with read binary rb mode:

with open('file.bin', 'rb') as f:
	data = f.read()

See also:

• bytes instances are incompatible with str instances