Logistic Regression :
logistic regression is a supervised learning algorithm used for classification problems. It is mainly used for binary classification. the target variable is categorical. the algorithm predicts the group which the current object belong.
it predicts the group by estimating the probabilities based on weightage relationship between dependent and independent variable. for this probabilities it uses the logistics function. the task of logistic function is to take any real value and map it between 0 and 1. then this values are converted into binary values 0 and 1 using threshold value. default threshold value is 0.5