1. A computer-implemented method, comprising: providing, at a server computing device having one or more processors, a user interface to a first client computing device, the user interface including a digital content item capable of being output by the first client computing device; receiving, at the server computing device, a signal from the first client computing device via the user interface to initiate a communication session regarding the digital content item; responsive to receiving the signal, initiating, at the server computing device, the communication session, wherein the communication session enables communication between the first client computing device and one or more other client computing devices; determining, by the server computing device, a context for a topic of discussion associated with the communication session based on the digital content item; based on the context of the communication session, selecting, by the server computing device, a subset of the one or more other client computing devices to invite to participate in the communication session, wherein each one of the one or more other client computing devices is selected when its user is associated with the context of the communication session; sending, by the server computing device, an invitation to each other client computing device of the subset of the one or more other client computing devices to join the communication session, wherein the invitation indicates the context of the communication session; and responsive to receiving a response signal in response to the invitation from a particular other client computing device of the subset of the one or more other client computing devices, connecting the particular other client computing device to the communication session.
1. A computer-implemented method, comprising: providing, at a server computing device having one or more processors, a user interface to a first client computing device, the user interface including a digital content item capable of being output by the first client computing device; receiving, at the server computing device, a signal from the first client computing device via the user interface to initiate a communication session regarding the digital content item; responsive to receiving the signal, initiating, at the server computing device, the communication session, wherein the communication session enables communication between the first client computing device and one or more other client computing devices; determining, by the server computing device, a context for a topic of discussion associated with the communication session based on the digital content item; based on the context of the communication session, selecting, by the server computing device, a subset of the one or more other client computing devices to invite to participate in the communication session, wherein each one of the one or more other client computing devices is selected when its user is associated with the context of the communication session; sending, by the server computing device, an invitation to each other client computing device of the subset of the one or more other client computing devices to join the communication session, wherein the invitation indicates the context of the communication session; and responsive to receiving a response signal in response to the invitation from a particular other client computing device of the subset of the one or more other client computing devices, connecting the particular other client computing device to the communication session. 9. The computer-implemented method of claim 1 , wherein sending the invitation comprises sending a notification signal while the communication session is in progress, the notification signal indicating that the communication session is in progress and may be joined, wherein receipt of the notification signal causes each of the subset of the one or more other client computing devices to display a touch-target notification associated with the digital content item that, when selected, causes each of the subset of the one or more other client computing devices to join the communication session.