From UserCentered.net, an overview of moderated remote research, which they call “remote synchronous research”.

‘Remote user research and testing’ is where the user and the facilitator are in different places. Remote user research can fall into two categories, ‘synchronous’ and ‘asynchronous’.

• In synchronous protocols, a facilitator interacts with a participant who is remote and leads the research activities in real time.
• In asynchronous protocols, observers do not have access to the participants in real time, and there is no facilitator interacting with them during data collection.

Synchronous methods are enabled by online conferencing tools. Online conferencing tools allow two or more users to share their desktop, open an audio channel, record the video of the sharing session, send files or links via a chat, and much more. Usability practitioners now have a wide choice of online conferencing tools. The most famous are Web-Ex, GoToMeeting and Yugma, but there are many tools offering similar features on the market.