Short answers, pulled from the story.
The first SWAT unit was created on the 1st of January 1964 in Philadelphia by the police department to handle the alarming rise in armed robberies. This unit was known as Special Weapons and Tactics and consisted of 100 specially trained officers.
Inspector Daryl Gates led the Los Angeles Police Department unit established in 1967. Deputy Chief Edward M. Davis insisted on the name Special Weapons and Tactics instead of the acronym Special Weapons Attack Team that Gates initially envisioned.
The first significant deployment of the LAPD SWAT team occurred on the 9th of December 1969 during an attempt to serve arrest warrants against the Black Panthers. This event led to a four-hour standoff at their Los Angeles headquarters at 41st and Central where over 5,000 rounds were exchanged.
By 2015, the number of annual SWAT deployments in the United States had increased to nearly 80,000 times a year. Most of these deployments were used to serve drug-related warrants in private homes.
During the Columbine High School massacre on the 20th of April 1999, officers set a perimeter and did not intervene in the shooting until 12 people were killed. The perpetrators Eric Harris and Dylan Klebold committed suicide, and the delayed response led to criticism regarding the death of teacher Dave Sanders.
Chinese Public Security SWAT units perform extra duties such as riot control, disaster relief, and prison security beyond counter-terrorism and active shooter response. They are sometimes known as Patrol SWAT and may handle police dogs or firefighting within prisons.