The proxy bookmarklet lets you reload a web page through the U-M Library's proxy server. If the page you are visiting is one that the library has a subscription for, and you're presently off-campus, then you should get you immediate access to the resource once you've logged in with your uniqname and Kerberos password and have been verified to have a valid library account.
University of Michigan students, faculty, can access most restricted electronic library resources from off-campus once they provide evidence of their affiliation with the U of M.
The Proxy Server is a tool that lets you log into your library account to "authenticate" as a UM affiliate. Watch this screencast for more information.
To log into the proxy server from off campus:
The proxy server example is the better choice if you are working from a public computer where you aren't allowed to install the bookmarklet.