Classifiers are algorithms used in machine learning and artificial intelligence to categorize data into predefined classes or labels. They analyze input data, such as images, text, or numerical values, and assign it to the most appropriate category based on learned patterns from training data. Common examples of classifiers include decision trees, support vector machines, and neural networks. In practical applications, classifiers are used in various fields, such as spam detection in emails, image recognition in photos, and sentiment analysis in social media. By automating the classification process, they help organizations make informed decisions and improve efficiency.