Persistent Cookies <p>A persistent cookie is a small piece of text stored on your computer's hard drive for a defined period of time, after which the cookie is erased. We do not collect or link to personal information through persistent cookies without your express consent. We use persistent cookies as follows:</p> <ul> <li> <p>Site usage measurement—Our site measurement tool uses a persistent cookie to assist us in measuring how and when our Web site and its various components are used. It functions as a "visit cookie," so that we can determine if you are a repeat visitor to our site. This allows us to know if we are attracting new visitors and what aspects of the site seem most useful. The cookie will expire 30 days after your last visit.</p> </li>