What is the difference between the null hypothesis, alternate hypothesis, directional hypothesis and non-directional hypothesis?

A hypothesis is a statement about the relationship between two variables (usually, the IV and the DV). The statement must usually also be operationalised or 'testable', which is another way of saying made more specific so that the researcher knows exactly how to go about studying the relationship between the two variables based on. A null hypothesis is an assumption of no relationship between the two variables, hence 'null', e.g. There is no relationship between [IV] and [DV]. This is the hypothesis that the researcher will attempt to reject by disproving it, thus approving the alternate hypothesis.An alternate hypothesis (also called an experimental hypothesis) is what you'd assume to be a hypothesis normally. It's called the 'alternate' hypothesis because it acts as the alternative to the null hypothesis, e.g. There is a positive correlation between ___ and ___. A directional/non-directional hypothesis is a more specified version of the alternate hypothesis. A directional hypothesis notes the direction in which the predicted difference or relationship between the variables will go e.g. Group A will be significantly better/worse than Group B in Activity A. A non directional hypothesis simply predicts there will be a difference between the variables without specifying its direction e.g. There will be a difference between Group A and Group B in Activity A.