Employers will ask candidates for references. This formal request is probably not the only digging they will do. Much has been said about your web-presence, but it is also important to know that besides googling your name and using the references you provide, they will probably do some informal reference checking of their own.
There is one company I know of that had offered someone a job. Upon discussing the new hire candidate with company colleagues, a lot of less than positive information was revealed. Actually, I am not sure how this didn't come up prior to the offer being made, but it didn't. At least the manager was forewarned of potential issues.
Your professional reputation spills out further than your supervisors and "references". Any one who has previously worked with you can be used as a source of information. In most cases, there is no need for past co-workers to be anything other than candid.
The take-away from this is that we must be "like-able" and have a reputation for being easy to get along with as well as getting the job done.
On the formal reference checking side, there are some questions that are typically asked and answered in checking references. To learn more about the reference checking process, you can read this article in CIO Magazine by Jeffery Shane.
Hannah Morgan speaks and writes about job search and career strategies. She founded CareerSherpa.net to educate professionals on how to maneuver through today’s job search process. Hannah was nominated as a LinkedIn Top Voice in Job Search and Careers and is a regular contributor to US News & World Report. She has been quoted by media outlets, including Forbes, USA Today, Money Magazine, Huffington Post, as well as many other publications. She is also author of The Infographic Resume and co-author of Social Networking for Business Success.