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Welcome to CS 101. I'm Dave Evans. I'll be your guide on this journey.

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This course will introduce you to the fundamental ideas in computing

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and teach you to read and write your own computer programs.

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We're going to do all that in the context of building a Web search engine.

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I'm guessing everyone here has at least used a search engine before.

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The goal of the first three units in this course is to build a Web crawler.

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They will collect data from the Web for our search engine.

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And to learn about big ideas in Computing by doing that.

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In Unit 1, we'll get started by extracting the first link on a web page.

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A Web crawler finds web pages for our search engine

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by starting from a "seed" page and following links on that page to find other pages.

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Each of those links lead to some new web page, which itself could have links that lead to other pages.

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As we follow those links, we'll find more and more web pages

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building a collection of data that we'll use for our search engine.

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A web page is really just a chunk of text that comes from the Internet into your Web browser.

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We'll talk more about how that works in Unit 4.

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But for now, the important thing to understand is that

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a link is really just a special kind of text in that web page.

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When you clic on a link in your browser it will direct you to a new page.

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And you can keep following those links (...)

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What we'll do in this Unit is write a program to extract that first link from the web page.

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In later units, we'll figure out how to extract all the links and build their collection for our search engine