For handling a few strings in separate variables, see How do I append one string to another in Python?. For the opposite process – creating a list from a string – see How do I split a string into a list of characters? or How do I split a string into a list of words? as appropriate.

https://stackoverflow.com/questions/12453580/how-to-concatenate-join-items-in-a-list-to-a-single-string