The F-test in regression is a statistical test used to determine if there is a significant relationship between the dependent variable and the independent variables in a regression model. It compares the model with the independent variables to a simpler model with no independent variables (just the mean of the dependent variable). If the F-test shows a significant result, it indicates that at least one of the independent variables is useful for predicting the dependent variable. In simpler terms, it helps assess whether the overall regression model is effective at explaining the variation in the data.