aka "single"  or "45 rpm record" - A round disc made of vinyl with grooves that contains recorded spoken words and music. These discs with a large center hole were usually black in color but would sometimes be produced in solid and clear colors like yellow and red. This format was used during the last half of the 20th century but faded from use when the record companies found they could charge 3 to 5 times more when forcing consumers to purchase entire albums instead of individual "45's". Songs were usually labeled "A" or "B" to indicate which song the music company was trying to push. Songs lasted approximately 2 to 3 minutes in length.

Unfortunately some announcers were either unable to read or they didn't know that "A" meant "play this song". Several record companies resorted to removing the "B" songs and producing a single with only one song. Thus forcing announcers to only play the intended song and giving us two sides to scratch up instead of one.

Additional Information You Didn't Ask About
It has been long said that the large center holes of the "45" were designed to allow announcers (sometimes referred to an "disc jockeys") to rapidly remove and install a record on a moving turntable thus allowing the announcers to talk while holding pages of printed text (news, weather commercials, etc.) in their left hands while facing the microphone, while an engineer snuck under the board (a desk the announcer used in the studio) and lit the papers at the bottom, all while the announcer was changing the "45" with his or her right hand entirely by "feel".  Also very handy when those bathroom breaks lasted longer than the current song being played.