# Python Base64 Module

The `base64` module provides functions for encoding binary data to printable ASCII characters and decoding such encodings back to binary data. It provides encoding and decoding functions for the data encoding specified in RFC 3548, which defines the Base16, Base32, and Base64 algorithms, and for the de-facto standard Ascii85 and Base85 encodings.

## Importing the Module

```python
import base64
```

## Base64 Encoding

`base64.b64encode()` encodes a bytes-like object using Base64 and returns the encoded bytes.

```python
import base64

data = b"Python is fun"
encoded = base64.b64encode(data)
print(encoded)
# Output: b'UHl0aG9uIGlzIGZ1bg=='
```

## Base64 Decoding

`base64.b64decode()` decodes the Base64 encoded bytes-like object or ASCII string and returns the decoded bytes.

```python
decoded = base64.b64decode(encoded)
print(decoded)
# Output: b'Python is fun'
```

## URL Safe Encoding

The standard Base64 alphabet uses `+` and `/`, which are not URL-safe. The `urlsafe_b64encode()` function uses `-` and `_` instead.

```python
import base64

data = b"i\xb7\x1d\xfb\xef\xff"
standard_encoded = base64.b64encode(data)
url_safe_encoded = base64.urlsafe_b64encode(data)

print("Standard:", standard_encoded) # Contains + and /
print("URL Safe:", url_safe_encoded) # Contains - and _
```

## Encoding Strings

Since `b64encode` expects bytes, you often need to encode strings to bytes first, and decode the result back to a string if you want text output.

```python
import base64

message = "Hello World"
message_bytes = message.encode('ascii')
base64_bytes = base64.b64encode(message_bytes)
base64_message = base64_bytes.decode('ascii')

print(base64_message)
```

[[programming/python/python]]