Regression algorithms are a type of statistical method used in machine learning to predict a continuous outcome based on one or more input variables. They analyze the relationship between the dependent variable (the outcome) and independent variables (the predictors) to create a model that can make predictions on new data. Common types of regression algorithms include linear regression, which assumes a straight-line relationship, and polynomial regression, which can model more complex, curved relationships. These algorithms are widely used in various fields, such as finance, healthcare, and marketing, to forecast trends and make informed decisions.