The wb indicates that the file is opened for writing in binary mode.
When writing in binary mode, Python makes no changes to data as it is written to the file. In text mode (when the b is excluded as in just w or when you specify text mode with wt), however, Python will encode the text based on the default text encoding. Additionally, Python will convert line endings (\n) to whatever the platform-specific line ending is, which would corrupt a binary file like an exe or png file.
Text mode should therefore be used when writing text files (whether using plain text or a text-based format like CSV), while binary mode must be used when writing non-text files like images.
References:
https://docs.python.org/3/tutorial/inputoutput.html#reading-and-writing-files https://docs.python.org/3/library/functions.html#open
That is the mode with which you are opening the file. "wb" means that you are writing to the file (w), and that you are writing in binary mode (b).
Check out the documentation for more: clicky
Source: Stackoverflow.com