Input variables are the factors or elements that are used in a model or experiment to produce an outcome. They can be numbers, categories, or any measurable data that influence the results. For example, in a simple math equation, the numbers you plug in are the input variables that determine the final answer. In the context of data analysis or machine learning, input variables are often referred to as features. These features help algorithms learn patterns and make predictions. For instance, in a model predicting house prices, input variables might include square footage, number of bedrooms, and location.