Searching the Web

With billions of pages, you could spend a lifetime surfing the Web, following links from one page to another. Amusing perhaps, but not very efficient if you're seeking some specific information. So where do you start? Searching the Web requires part skill, part luck and a little bit of art. Fortunately, a number of free online resources help with the hunt.

You've probably heard of search engines such as Yahoo!, Google, and Bing. There are literally dozens of these tools to help you locate what you're looking for. The trick is understanding how they work so you can use the right one for the job.

Search engines break down into two types: directories and indexes. Directories, such as Yahoo!, are good at identifying general information. Like a card catalog in a library, they classify websites into categories, such as accounting firms, English universities and natural history museums. The results of your search will be a list of websites related to your search term. For instance, if you are looking for natural history museums, you might use a directory to find it.

But what if you want specific information, such as biographical information about Leonardo da Vinci? Web indexes are the way to go, because they search all the contents of a website. Indexes use software programs called spiders and robots that scour the Internet, analyzing billions of web pages, newsgroup and blog postings, and indexing all of the words. Some also index audio, video and images.

Indexes like Google and Bing identify the text on individual pages of a website that match your search criteria, even if the site itself has nothing to do with what you are looking for. You can often find unexpected gems of information this way, but be prepared to wade through a lot of irrelevant information too.

Search results are usually ranked in order of relevancy--the number of times your search term appears in a document--or how closely the document appears to match a concept you have entered. This is a much more thorough way to locate what you want.

Let's perform an online search using three popular search engines--Yahoo!, Google, and Ask--so you can see how they work and how you can develop an efficient search strategy.

Here's the challenge: You're planning a trip to San Francisco and you've always wanted to ride a cable car. Do they operate in January and if so, what's the schedule?

First we'll try Yahoo! One trick when searching is to narrow your focus. Entering "San Francisco" in the search box results in over millions of pages of information related to the City by the Bay! Entering "cable cars" also results in millions of pages, many of which have nothing to do with San Francisco. By combining the terms ("San Francisco cable cars") we've narrowed the search greatly. Now you have to visit each page to see if there's any information about cable car schedules. Fortunately, the first three sites listed all contain information pertinent to our search.