"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."