History, Evolution, and Practices of the President's State of the Union Address: Frequently Asked Questions [Updated January 29, 2020] [open pdf - 905KB]
From the Summary: "The State of the Union address is a communication from the President to Congress in which the chief executive reports on the current condition of the United States and provides policy proposals for the upcoming legislative year. [...] This report takes the format of answers to frequently asked questions about the State of the Union address."
CRS Report for Congress, R44770
Congressional Research Service: https://crsreports.congress.gov/