15. A non-transitory computer-readable medium storing instructions, the instructions comprising: one or more instructions which, when executed by a processor, cause the processor to: generate a graph by representing users and comments as nodes in the graph, and connecting the nodes based on relationships between the users and the comments, relationships between the comments, and relationships between the users; obtain a first initial score for a user and a second initial score for a comment authored by the user; calculate a user ranking score for the user and a comment ranking score for the comment based on the first initial score for the user, the second initial score for the comment, and the relationships between the nodes in the graph, the user ranking score reflecting a reputation of the user, the comment ranking score reflecting a quality of the comment; run iterations of a graph algorithm to determine if the user ranking score for the user and the comment ranking score for the comment authored by the user have converged based on the graph; generate, in response to determining that the user ranking score and the comment ranking score have converged, a ranked list of users, the ranked list including information identifying the user and being ordered based on both the user ranking score and the comment ranking score; and provide, for presentation, the ranked list.
15. A non-transitory computer-readable medium storing instructions, the instructions comprising: one or more instructions which, when executed by a processor, cause the processor to: generate a graph by representing users and comments as nodes in the graph, and connecting the nodes based on relationships between the users and the comments, relationships between the comments, and relationships between the users; obtain a first initial score for a user and a second initial score for a comment authored by the user; calculate a user ranking score for the user and a comment ranking score for the comment based on the first initial score for the user, the second initial score for the comment, and the relationships between the nodes in the graph, the user ranking score reflecting a reputation of the user, the comment ranking score reflecting a quality of the comment; run iterations of a graph algorithm to determine if the user ranking score for the user and the comment ranking score for the comment authored by the user have converged based on the graph; generate, in response to determining that the user ranking score and the comment ranking score have converged, a ranked list of users, the ranked list including information identifying the user and being ordered based on both the user ranking score and the comment ranking score; and provide, for presentation, the ranked list. 19. The medium of claim 15 , where the instructions further include: one or more instructions to receive a request for comments associated with a document; one or more instructions to rank, based on the request and using the comment ranking score, the comments; and one or more instructions to provide, for presentation in the ranked list, a subset of the comments.