West End Blues by Louis Armstrong is one of the most important songs in jazz. A YouTube poster named pandasthumb describes the piece. It’s definitely worth checking out. Here is one paragraph from the post:
From the very first note of “West End Blues,” a tune composed by Joe “King” Oliver, one can immediately sense the shift that was occurring in jazz through Armstrong’s influence. From his introductory, fanfare-like opening to his solo later in the recording, Armstrong displays his power, range, and unique personality on the trumpet. Pianist Earl Hines is also featured.
Pandasthumb annotates the video with a description of what is going on and why it is special.