The original paper[0], published in '86, in addition to being a huge step forward over contemporary graphics techniques, is extremely comprehensible and an excellent read. It also goes into some detail about collision avoidance, which is hard to see in the browser demo (boids will avoid the mouse but not in a very large area), and goal seeking, which isn't in it. It ends with a fairly eyebrow-raising testament to the increase in computer power over the last two and a half decades:<p>"This report would be incomplete without a rough estimate of the actual performance of the system. With a flock of 80 boids, using the naive O(N^2) algorithm (and so 6400 individual boid-to-boid comparisons), on a single Lisp Machine without any special hardware accelerators, the simulation ran for about 95 seconds per frame. A ten-second (300 frame) motion test took about eight hours of real time to produce."<p>[0] <a href="http://www.red3d.com/cwr/papers/1987/boids.html" rel="nofollow">http://www.red3d.com/cwr/papers/1987/boids.html</a>