Groups of users accessing content are generated and modified to allow the users to more easily interact with each other. A number of groups and a maximum number of users in a group are received and used to generate shards. In one embodiment, the number of shards generated is based on the number of groups received. Each shard is associated with a unique shard identifier. In one embodiment, a user is associated with a shard when the user accesses content. For example, when a comment is received from a client device associated with a user, a user identifier is determined and associated with a shard. Using the shards, groups of users are generated. In one embodiment, a substring of the shard identifiers associated with the shards is determined and users associated with shard identifiers having the same substring of the shard identifier are included in a group.