source domain

A source domain refers to the original area or context from which knowledge, data, or concepts are derived. In the context of machine learning or data analysis, it’s the dataset or information used to train a model before applying it to a different, but related, area called the target domain. For example, training an email spam filter using data from English-language emails is the source domain. Understanding the source domain helps in assessing how well the model might perform when used in a different context or with different data.