Lots to read here: tangomusicology.com - obviously a labour of love by a knowledgeable and curious person. There's really a lot there. Of interest to musicians, but also with basic explanations for those with no or (like me) rudimentary musical literacy; and, delightfully, videos synchronising the sound as closely as possible with the written scores. [Edit - fixed link - sorry!]
Here's the author's summary from the home page:
My analysis aims to capture and describe the character of the music. I use the latest music notation tools and plenty of audio clips to explore this rich music in depth, in an informative and hopefully enjoyable format. There is a standardized methodology and approach. Each starts with a big picture view of the music then delves deeper and deeper into its essence. Generally, these are the elements I write about:
Structure or Form; Phrases, sub-phrases, at one and two levels below the primary phrase; Phrasing: Question and Answer qualities, Dynamics, Articulation; Melody, Melodic Shape, Melodic Rhythms, Counter Melodies; Harmonies, Keys, Modulation, Cadence; Accompaniment, marking the beat, syncopation and rhythmic patterns, fills and transitions between phrases; Orchestration, texture.Plus anything else I see and hear in the music. These elements are the foundation of music, its composition and performance.