1973: "Dj Koolherc's" first jam 1520 sedgwick ave. ,bronx, nyc it would be for his sisters birthday party his style of music was made to get the crowd jumpin, he did that by buying to copies of each record and elongating the break part (the funky drum solo section) of the record by mixing in both records before the break would end. thus was born what we call today "break beats'
1973: around this time young dancers would hit the parties that kool herc was playing at and the music that herc played inspired these young cats to do moves that would lay the foundation for hip hop dance. herc seeing these young dancers would eventually call them "bboys" (as well as people who would show up to jams and break sh&t up) which would later be interpreted as break boys, beat boys, or bronx boys.
1974: "Dj Grand Wizard Theodore" invents the scratch while trying to hold a record in place while his mother was yelling at him. the needle was still on the record so it made that shiga shiga sound which he later on turned into the scratch.
Late 1970s: Grand Master Flash becomes the most avant garde of all the dj's , and starts setting trends for style and technical skills.
1981: Grand Master Flash releases one of the greatest dj records of all time "the adventures of grand master flash on the wheels of steel"
1983: "Grand Mixer Dst" lends his skills to legendary musician herbie handcock to record the top hit "rockit"
1980s - current: Even though dj'ing has receded into the background behind the mc(s), the dj'ing culture still thrives, and has done so in a variety of formats, especially the "battling" formats, as in the dmc national battles and so on.