Monitoring is essential to ensure that a website is available to users, downtime is minimized, and performance can be optimized. Users that rely on a website, or an application, for work or pleasure will get frustrated or even stop using the application if it is not reliably available. Monitoring can cover many things that an application needs to function, like network connectivity, Domain Name System records, database connectivity, bandwidth, and computer resources like free RAM, CPU load, disk space, events, etc. Commonly measured metrics are response time and availability (or uptime), but consistency and reliability metrics are gaining popularity. Measuring a website's availability and reliability under various amounts of traffic is often referred to as load testing.