An encoder is a device or software that converts information from one format to another, often for the purpose of efficient transmission or storage. For example, in digital communication, encoders transform analog signals into digital data, making it easier to send over networks. They are widely used in various applications, including audio and video compression, where they help reduce file sizes while maintaining quality. In the realm of machine learning, encoders are used to convert categorical data into numerical formats that algorithms can process. A common type is the one-hot encoder, which creates binary columns for each category, allowing models to interpret the data effectively. Encoders play a crucial role in data preprocessing, enhancing the performance of machine learning models.