Data can be quantitative or qualitative values that are collected from various sources. There are two main types of data sources: internal sources which are from within an organization, and external sources which are outside. External data can be primary data collected directly from original research, or secondary data that has already been collected for other purposes. Primary data collection methods include surveys, interviews, and observations, while secondary data comes from published sources like reports and unpublished sources. The main difference between primary and secondary data is that primary data involves direct collection while secondary data has already been collected previously.