"Unlike text files, Web pages generally divide text with tags and other markers rendered into lines by the browser. A wide variety of browser window sizes makes it difficult to isolate nearby text based on expected line positions. Tables, links, and other text markup also make it difficult to isolate text that is in the same "line."
"Algorithms in this article are designed to address some of these difficulties by providing a simple grep-like functionality piped to a function that works like grep's -v option. This allows the user to find a certain word of text, then only highlight entries where a different word is not nearby. Figure 1 shows what this can look like."
