BACKGROUND

Many companies and other organizations operate computer networks that interconnect numerous computing systems to support their operations, such as with the computing systems being co-located (e.g., as part of a local network) or instead located in multiple distinct geographical locations (e.g., connected via one or more private or public intermediate networks). For example, distributed systems housing significant numbers of interconnected computing systems have become commonplace. Such distributed systems may provide back-end services to web servers that interact with clients. Such distributed systems may also include data centers that are operated by entities to provide computing resources to customers. Some data center operators provide network access, power, and secure installation facilities for hardware owned by various customers, while other data center operators provide “full service” facilities that also include hardware resources made available for use by their customers. However, as the scale and scope of distributed systems have increased, the tasks of provisioning, administering, and managing the resources have become increasingly complicated.

For example, distributed systems may be used to implement Internet-accessible services such as discussion forums and social media networks. Discussion forums and social media networks may permit millions of users to post text, images, video, and other forms of user-provided content. Some content provided by users to a particular service may violate content standards of the service, and the service may seek to remove the offending content. To identify such content, services may employ large numbers of human content reviewers who manually review user-provided text, images, and video. Such manual review may be expensive for the service, time-consuming for the reviewers, and prone to human error because individual reviewers may differ in their approaches.

