Published at LXer:

Firebug is popular because it solves the long-standing problem of debugging Web pages. Before Firebug, the two main methods for debugging Web applications were the server's error log (to which all error-related data was sent) and the HTML source code (making the debugging output visible to all users via the "view source" function). But with JavaScript becoming an increasingly important player in the creation of dynamic Web sites, and with CSS (cascading stylesheets) determining the formatting, the combination of error logs and "view source" was getting painfully difficult.

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