The IE Developer Toolbar is very useful for web developers to understand and analyze webpages. It provides several features for deeply exploring and understanding Web pages.
Quoted from Microsoft website
— Explore and modify the document object model (DOM) of a web page.
— Locate and select specific elements on a web page through a variety of techniques.
— Selectively disable Internet Explorer settings.
— View HTML object class names, ID’s, and details such as link paths, tab index values, and access keys.
— Outline tables, table cells, images, or selected tags.
— Validate HTML, CSS, WAI, and RSS web feed links.
— Display image dimensions, file sizes, path information, and alternate (ALT) text.
— Immediately resize the browser window to 800×600 or a custom size.
— Selectively clear the browser cache and saved cookies. Choose from all objects or those associated with a given domain.
— Choose direct links to W3C specification references, the Internet Explorer team weblog (blog), and other resources.
— Display a fully featured design ruler to help accurately align objects on your pages.
The Developer Toolbar can be pinned to the Internet Explorer browser window or floated separately.