Short answers, pulled from the story.
The Philadelphia Police Department formed a 100-man specialized unit called Special Weapons and Tactics in 1964 to combat an alarming rise in bank robberies. This group used specially trained officers with heavy firepower to stop crimes while they were happening.
Inspector Daryl Gates initially wanted the acronym to mean Special Weapons Attack Team but Deputy Chief Edward M. Davis insisted on Special Weapons and Tactics instead. The LAPD unit grew from fifteen teams of four men each into a sixty-person staff that met for monthly training sessions.
Over 5,000 rounds were exchanged between officers and members of the group before they surrendered during a four-hour standoff. This event marked the first major deployment when police faced heavily armed criminals at the Black Panthers headquarters.
Paramilitary units launched only a few hundred drug raids annually in 1972 but numbers jumped to 3,000 by the early 1980s. By 1996, departments conducted 30,000 raids every year across the United States as part of the war on drugs.
A siege in the Winnetka neighborhood of Los Angeles on the 7th of February 2008 resulted in the first line-of-duty death for an LAPD SWAT member in forty-one years. Analyst Radley Balko argued that increased raids made no-knock entries far more dangerous for both innocents and suspects.
Ballistic vests labeled POLICE or SHERIFF became standard issue with rigid plate inserts for extra protection while teams carry special weapons including assault rifles and sniper rifles. Armored vehicles called Lenco BearCat allow insertion and maneuvering during operations involving fire from suspects alongside ballistic shields and battering rams.