9. A system for enforcing parental-control policies on user-generated content comprising: a detection module programmed to: identify a web document, the web document comprising user-generated content that is not authored by an entity that publishes and/or hosts the web document; identify a subset of links in the web document that are related to the user-generated content in the web document by: 1) parsing the web document to identify a set of links in the web document; 2) identifying, within the set of links, one or more links which are related to the user-generated content by determining that the one or more links refer to the user-generated content, by determining that the user-generated content includes the one or more links, and/or by determining that the one or more links refer to a content-generating user responsible for generating the user-generated content; 3) excluding, from the subset of links, one or more links identified in the set of links that were not determined to be related to the user-generated content in the web document; 4) including, in the subset of links, the one or more links that were determined to be related to the user-generated content in the web document; a rating module programmed to: for each link in the subset of links: identify a target web document of the link; determine a parental-control rating for the link based on the target web document; generate a composite rating of the web document based, at least in part, on the parental-control rating of each link in the subset of links; enforce the parental control policy based on the composite rating of the web document; one or more processors configured to execute the detection module and the rating module.
9. A system for enforcing parental-control policies on user-generated content comprising: a detection module programmed to: identify a web document, the web document comprising user-generated content that is not authored by an entity that publishes and/or hosts the web document; identify a subset of links in the web document that are related to the user-generated content in the web document by: 1) parsing the web document to identify a set of links in the web document; 2) identifying, within the set of links, one or more links which are related to the user-generated content by determining that the one or more links refer to the user-generated content, by determining that the user-generated content includes the one or more links, and/or by determining that the one or more links refer to a content-generating user responsible for generating the user-generated content; 3) excluding, from the subset of links, one or more links identified in the set of links that were not determined to be related to the user-generated content in the web document; 4) including, in the subset of links, the one or more links that were determined to be related to the user-generated content in the web document; a rating module programmed to: for each link in the subset of links: identify a target web document of the link; determine a parental-control rating for the link based on the target web document; generate a composite rating of the web document based, at least in part, on the parental-control rating of each link in the subset of links; enforce the parental control policy based on the composite rating of the web document; one or more processors configured to execute the detection module and the rating module. 13. The system of claim 9 , wherein the rating module enforces the parental-control policy by: identifying an attempt to submit user-generated content; blocking the attempt to submit user-generated content.