Data linkage is the process of combining information from different sources to create a more complete dataset for research or analysis purposes. This can involve linking data from multiple sources such as surveys, administrative records, and clinical databases to generate new insights and improve the accuracy of findings. Data linkage is commonly used in fields such as public health, social sciences, and economics to conduct large-scale studies and identify patterns or trends that may not be apparent when using individual datasets in isolation. It requires careful consideration of privacy and security concerns to protect the confidentiality of individuals' data and ensure ethical practices are followed.