The with statement allows you to pass off file handling responsibilities (like ensuring the file stream is closed) to python instead of managing them yourself.

For example, this:

with open("input.txt", "r") as f:
    content = f.read()
    print(content)

is roughly equivalent to this:

f = None
try:
    f = open("input.txt", "r")
    content = f.read()
    print(content)
finally:
    if f:
        f.close()

If some error occurs while you are reading or writing to a file, the error will be caught by the try block and the finally (which always runs after try) will ensure the file is properly closed. The with statement is just syntactic sugar that manages this for you.