any process of preparing and collecting data
Data collection is any process of preparing and collecting data, for example, as part of a process improvement or similar project. The purpose of data collection is to obtain information to keep on record, to make decisions about important issues, or to pass information on to others. Data are primarily collected to provide information regarding a specific topic.
Questions having the data-collection tag regards the act of collecting data, how it affects users, and what type of data to collect in the context of User Experience.
Reference: Wikipedia - Data Collection