Used car price prediction using machine learning involves building a predictive model that can estimate the price of a used car based on various features such as the car's age, mileage, model, make, and condition. This is typically achieved by using supervised learning techniques such as regression analysis or decision trees to analyze and learn from a dataset of past car sales transactions. The trained model can then be used to make predictions on new or unseen data, enabling car dealerships, buyers, and sellers to make informed decisions about pricing and purchasing. The accuracy of the predictions depends on the quality and quantity of the data used to train the model, as well as the complexity of the model itself.