Whats the difference between independent and dependent variables? also, theory and hypothesis?

Independent variable: the variable in an experiment which value is not changed based on any other variable. often denoted by "x"
dependent variable: the variable in an experiment which changes based on the value of the independent variable, ie how much of it you use, how often you use it, etc. often denoted by "y"

theory: an explanation as to why certain phenomena occur. supported and testable, but could change with new research / experiments, etc.
hypothesis: a guess or an estimate of what will happen during an experiment. testable, and may be wrong.

i hope this helps!!