Short answers, pulled from the story.
The Space Launch System emerged from a specific legal requirement in 2010 when Congress passed the NASA Authorization Act of 2010, Public Law 111, 267. This act directed NASA to create a new system for launching payloads and crew into space as the Space Shuttle program drew to a close in 2009.
The first launch required by Congress to take place by 2016 occurred nearly six years later on the 16th of November 2022. The launch was originally scheduled for the 29th of August 2022 at 8:30 am EDT before being postponed to the 3rd of September 2022 due to a temperature sensor issue.
NASA has spent $29 billion on SLS development from 2011 through 2024 in nominal dollars. This figure equals $35.4 billion in 2025 dollars using NASA New Start Inflation Indices.
Utah Senator Orrin Hatch ensured the new rocket used the Shuttle's solid boosters manufactured in his state while Alabama Senator Richard Shelby insisted that the Marshall Space Flight Center design and test the rocket. Florida Senator Bill Nelson brought billions of dollars to Kennedy Space Center to modernize its launch facilities.
Block 1B configuration with the purpose-built Exploration Upper Stage is to be introduced on the fourth flight. A further improved Block 2 configuration with new solid rocket boosters is planned for the ninth flight.