Web Performance Tuning

Colophon

Our look is the result of reader comments, our own experimentation, and feedback from distribution channels. Distinctive covers complement our distinctive approach to technical topics, breathing personality and life into potentially dry subjects.

The animal on the cover of Web Performance Tuning is a sword-billed hummingbird. There are over 300 species of hummingbird, all found only in the Americas. All of these species are easily identified by their long, tubular bills and iridescent feathers. The iridescence is a refraction effect that can be seen only when light is shining on the feathers at certain angles. Hummingbirds range in size from the bee hummingbird which, measuring 2 inches long and weighing less than an ounce, is the smallest of all birds, to the great hummingbird, which measures about 8.5 inches long.

Hummingbirds are so named because of the humming noise made by their rapidly moving wings. On average, hummingbirds flap their wings 50 times a second; some species can flap as many as 200 times per second. The wings are flexible at the shoulder and, unlike most birds, they are propelled on the upstroke as well as the downstroke. Because of this flexibility, hummingbirds can hover, fly right or left, backwards, and upside down. Most hummingbirds have tiny feet that are used only for perching, never for walking. Hummingbirds will fly to travel even a couple of inches.

Hummingbirds expend a great deal of energy, and need to feed every 10 minutes or so. They feed ...