I am sure you know some basic VSA/Wyckoff concepts.
In a nutshell, Wyckoff believed that trading was made up of buying and selling waves.
The comparison of these waves, looking in particular at the length and duration of these waves, and the amount of volume they contain,
gave an insight as to how strong the buyers, or the sellers, were at at certain junctures on the chart.
If you have 15 or 20 minutes available, watch this video, it will explain so much more than I can type out in the same amount of time.
And you will have a reasonable understanding of it when done.
It is a presentation by David Weis (possibly the world's highest authority of all things Wyckoff), for Big Mikes Trading.
The actual presentation goes for about 20 minutes, then there is an extended question and answer session.
The only thing I would add to this presentation, is that David shows mostly very clear examples, and only one that is a bit more difficult to interpret.
And in the real world, the set ups are not always as clear (sometimes they are though).
If you do watch it, use full screen, so you can see the numbers.
