Text classification is a machine learning subfield that teaches computers how to classify text into different categories. It is commonly used as a supervised learning technique, which means that the algorithm is trained on a set of texts that have already been labeled with their respective categories. Text classification is a versatile tool that is widely used in many real-world applications, such as email spam filtering, sentiment analysis, and categorizing news articles and videos. BERT, a powerful NLP model developed by Google, is an example of a text classification algorithm.