LIN 101: Introduction to Linguistics

The top-level domain part of a web site's address can tell a lot about the legitimacy of the site

.edu - linked to an educational institution (though this domain can host personal web pages as well.)
.org - non-profit organizations or associations
.gov - a governmental department or agency, or government officials
.com - a commercial site, online service, or a for-profit organization
.mil - U.S. military organizations
.int- international organizations
.net - networking organizations

Look for citations, or some form of verification for the information presented on a web site.

The name and address of an author of a web site is reassuring, though this does not necessarily guarantee authority or legitimacy.
 

Scholarly materials are written by and for faculty, researchers or scholars using scholarly or technical language, include full citations for sources. Scholarly items are often refereed or peer reviewed. Book reviews and editorials are not considered scholarly articles, even when found in scholarly journals.

Popular materials are often written by journalists or professional writers for a general audience using language easily understood by general readers. Popular items rarely give full citations for sources, are written for the general public, and tend to be shorter than scholarly materials.