Case folding is a text normalization process used in natural language processing (NLP) and information retrieval. It involves converting all characters in a text to a single case, typically lowercase, to ensure uniformity. This helps in comparing and matching words without being affected by their original casing. By applying case folding, systems can treat words like Apple and apple as identical, improving search accuracy and data analysis. This technique is particularly useful in tasks such as text classification, sentiment analysis, and information retrieval, where consistent representation of text is crucial for effective processing.