During the process of creating a video using Camtasia Studio, you'll be creating a series of different types of files. Some of these are proprietary to Camtasia Studio and some of these are more accessible (like mp4s). This guide gives you an overview of the different types of files and why they all have place in the video editing workflow.
It is highly recommended that you and store all your files at each step of the process.
TechSmith Recording File (.trec) and Camtasia Studio Projects (.camproj)
Camtasia Recorder has its own file type - .trec. When you create a recording via the Camtasia Recorder, a proprietary file called a .trec is created. This file can be opened for editing in Camtasia Studio, however, it cannot be uploaded to, say, youtube or another video hosting service. This is because it is a work file, and not a final file. You'll see this right away if you select on the "produce" button after recording as you will be prompted to save this file as a .trec file.
Camtasia Studio also has its own file type - .camproj. You can open a .trec file in Camtasia Studio. You can also import a number of different file types into Camtasia. Thus, the .camproj file is your working file - a collection place for editing all the pieces of your video together.
Usually, you don't share your work files - .trec and .camproj (although you might if you are working with a production team or if you are providing the work files for editing via an online repository). What you share are your production files, while are the rendered versions of your work files. Rendering your video is what takes it from a work file to a final (shareable) file. You can think of it like this - .trec and .camproj files are the building files - the ones where you add in all your extra graphics, pop ups, text, add ons, etc. - while your .mp4 or .mov (or others) are your final files - the ones that are just the movie and are not editable.