Traditionally, conforming is the process of combining shots and sounds from various artists into one master session. This process happens many times throughout a film's production to provide the artists with an updated master cut of the film, so they can see their shots in context. The editor has traditionally been bound to the two-dimensional media that the artists submit for the master. But now, with the SFM, the editor can work in the same three-dimensional space that the animators work in. All of the elements in a shot can be conformed into the master session individually or as a whole. One light can be copied to many shots, or one character's animation can be updated without disturbing the rest of the cast.
Because working with multiple sessions simultaneously can be risky, you may want to consider using a content management system, so that you can retrieve a previous version of your session if you do lose data.
To conform in the SFM, with one session open (session A), you use the Element Viewer to import a second session (session B). The Element Viewer contains two bins, the clipBin and the miscBin, which are designed to contain references to sessions and their components. By default, the clipBin contains a reference to session A's active clip, which is the part of the session that contains all the information you need to do conforming. Make sure to leave that reference in there. If you don't, it's extremely easy to permanently lose session A. Even Valve's internal SFM users have lost data that way.
You use the miscBin to import a reference to session B. You'll find the steps to guide you through this process in Importing a second session in the Element Viewer.
After you have imported session B in the Element Viewer, you can add shots from it into session A, replacing existing shots in session A with shots that have the same names, replace individual animation sets in session A with animation sets that have the same names, and copy visual effects and sound clips from session B to session A.
Once you have the reference to session B in the miscBin, you can also preview its active clip by dragging it into the viewport, which allows you to easily compare session A to session B. After dragging session B's active clip into the viewport, you can even edit any of session B's elements before conforming them into session A. For more information, see "Previewing the imported session" in Importing a second session in the Element Viewer.