1. A method comprising: determining, using one or more processors, an inferred interest for a first user; generating, using the one or more processors, a model based on the inferred interest of the first user and storing the model in a non-transitory storage medium; generating, using the one or more processors, a set of candidate content items using an item from a second user with a similarity to the first user; determining, using the one or more processors, a first attribute and a second attribute associated with a candidate content item in the set of candidate content items; determining, using the one or more processors, a first score associated with the first attribute for the candidate content item based on the model of the first user and a first number of candidate content items having the first attribute in the set of candidate content items; determining, using the one or more processors, a second score associated with the second attribute for the candidate content item based on the model of the first user and a second number of candidate content items having the second attribute in the set of candidate content items; computing, using the one or more processors, a third score for the candidate content item in the set of candidate content items by summing the first score associated with the first attribute and the second score associated with the second attribute; selecting, using the one or more processors, content items for a stream of content associated with the first user from the set of candidate content items based on the third score of the content items; generating, using the one or more processors, an explanation for a first content item in the selected content items, the explanation indicating a reason for presenting the first content item to the first user; and transmitting, using the one or more processors, an instruction to a device that causes the device to present for display the stream of content to the first user with the explanation alongside the first content item, the explanation including a selectable graphic element for the first user to access an expanded explanation.