Strings

Silly question, but i understand how Single Quote and Double Quote Strings work, but what i wanted to know if you assign a string to include a variable so that it dynamically changes. Would that mean that i need to make the string Double Quote String, so that the server would send the string again so that it can be parsed each time and dynamically update, or can i make it a single quote, and then would it still dynamically update it. I hope everyone gets this. Sorry if it doesn't make sense. Let me know and ill try to include an example.