HTTP: The Definitive Guide

Chapter 2. URLs and Resources

Think of the Internet as a giant, expanding city, full of places to see and things to do. You and the other residents and tourists of this booming community would use standard naming conventions for the city’s vast attractions and services. You’d use street addresses for museums, restaurants, and people’s homes. You’d use phone numbers for the fire department, the boss’s secretary, and your mother, who says you don’t call enough.

Everything has a standardized name, to help sort out the city’s resources. Books have ISBN numbers, buses have route numbers, bank accounts have account numbers, and people have social security numbers. Tomorrow you will meet your business partners at gate 31 of the airport. Every morning you take a Red-line train and exit at Kendall Square station.

And because everyone agreed on standards for these different names, we can easily share the city’s treasures with each other. You can tell the cab driver to take you to 246 McAllister Street, and he’ll know what you mean (even if he takes the long way).

Uniform resource locators (URLs) are the standardized names for the Internet’s resources. URLs point to pieces of electronic information, telling you where they are located and how to interact with them.

In this chapter, we’ll cover:

• URL syntax and what the various URL components mean and do

• URL shortcuts that many web clients support, including relative URLs and expandomatic URLs

• URL encoding and character rules

• Common URL schemes ...