Code of Federal Regulations
The permanent, subject-organised codification of federal agency rules - what the Federal Register's daily output becomes.
The Code of Federal Regulations, the CFR, is the standing body of federal regulation arranged by subject across 50 titles. Where the Federal Register is a chronological record of what changed on a given day, the CFR is the answer to the question a compliance officer actually asks: what does the rule require right now.
The two are the same material at different stages. A final rule publishes in the Federal Register, then amends the CFR - which is why a citation to a requirement is almost always a CFR citation, while a citation to a decision is a Federal Register one.
What the federal government did, once a day.
One email each weekday: the rules, filings, votes and Fed decisions that actually changed something, each one linked to the document it came from.