NIST CSF

The National Institute of Standards and Technology developed its cybersecurity framework, aka The Framework for Improving Critical Infrastructure Cybersecurity, to strengthen the security of United States critical infrastructure. NIST’s goal was to establish a common set of standards, goals, and language to increase information security and better remediation of the fallout after a cyberattack. A common language leads to better decision making and helps to shape a similar methodology across industries, something that’s very desirable when it comes to eradication of cyberattacks like phishing schemes and ransomware.
Identify | Protect | Detect | Respond | Recover

NIST 800-53

The National Institute of Standards and Technology (NIST) is on the fifth revision (rev5) of Special Publication (SP) 800-53, Security and Privacy Controls for Information Systems and Organizations. From rev4 to rev5, NIST dropped the "US Government" focus for NIST SP 800-53 and now has it generalized enough for private industry to use. There are still "NISTisms" for wording that are entirely US Government-focused, but it is a significant improvement for private industry adoption. NIST 800-53 "best practices" are the de facto standard for private businesses that do business with the US federal government.
Defense Contractors (CMMC, RMF, etc.)
Government Contractors (FedRAMP, RMF, etc.)
Technology Businesses (e.g., MSPs, CSPs, etc.)
General Business (large)
Retail (large)
Healthcare (large) & Insurance (large)

NIST 800-171

The National Institute of Standards and Technology (NIST) is on the second revision (rev2) of Special Publication (SP) 800-171, Protecting Controlled Unclassified Information in Nonfederal Systems and Organizations. The US National Archives (NARA) runs the Controlled Unclassified Information (CUI) Program for the US Government and NARA specifies NIST SP 800-171 and 800-171A as the minimum requirements to protect CUI. NIST SP 800-171 is the basis for the controls used by the US Department of Defense's Cybersecurity Maturity Model Certification (CMMC). Used by:
Defense Contractors
Government Contractors
Technology Businesses (MSPs, MSSPs, etc.)