This is something I created for fun, after seeing similar examples online I decided to create my own version from scratch. It is a little interactive, you can create more particles by left clicking anywhere on the canvas.
Technical info
The particles and lines are drawn using the HTML5 Canvas element.
I used JavaScript to program the particle motion and line thickness.
I programed it so that a line is drawn between particles below a fixed distance. The lines also gets thinner with distance.