When diagnosing an issue, you need to think back to what was the last item that changed. It could be a code push that somehow removed analytics from your site, it could have been a change to content that has caused a decline in search traffic. Did you make a change to your advertising? Sudden declines (or increases) are often traceable back to the last modification (big or small) that was made. - Greg Kihlstrom, Yes& Agency
Web analytics is the measurement of the behavior of visitors to a website. In a commercial context, it especially refers to the measurement of which aspects of the website work towards the business objectives of Internet marketing initiatives; for example, which landing pages encourage people to make a purchase. Notable vendors of web analytics software and services include Google Analytics, IBM Digital Analytics (formerly Coremetrics) and Adobe Omniture.