You may see some of these terms used in some of the tutorials on the site. Hopefully the explanations here will make things easier to understand.
Use this dictionary to find out what many of the Poser options and settings do.
Focal: Sets the camera's focal length. Smaller focal lengths give a "fisheye" effect and larger focal lengths give a landscape effect. Think of the Focal setting as a camera lens. The focal settings do not translate exactly to real cameras but it's close enough to use it to have a general idea of how the Poser cameras are similar.
General Digital Camera settings: 35 mm
Human Eyes: 60 mm
Portrait lens 50 mm
Telephoto / Zoom lenes 135 mm
Perspective: Gives the camera zoom in and zoom out effects. Change the perspective settings for your camera to make your hallways appear longer or shorter. You'll find that most of the indoor 3D models have a cramp feel when placing objects and characters in that space. Your render will look cramped as well unless you change the perspective of the camera to add some depth to the scene.
Focus Distance: Sets the distance in which objects will be in focused. It allows you to set which objects you want to have in focus and which objects you want to have out of focus. It slows down rendering time when used.
F-Stop: Determines how much light to come in to the camera. It determines the depth of field for your render. The higher the F-Stop the deeper, the field of focus is.
Hither: Controls the location of the Clipping Plane. Anything between the camera and the clipping plane will not appear in the preview window.
Yon: Controls the far end of the clipping plane. Anything that is beyond the end of the clipping plane will not appear in the preview window.
I haven't had any need to know what these are with the exception of OBJ. Most users probably don't need to know any of the file extensions beyond OBJ unless the person is planning on creating their own content.
BUM: Bump map files that give the content a bumpy appearance.
CM2: Camera files
CR2: Poseable or conforming figure files
FC2: Face poses that are associated with the morphs of a figure's face
HD2: Hand Poses
LT2: Light sets
OBJ: Wavefront Object geometry file
PMD: External morph data files.
PP2: Prop files
PY: Pyton Scripts
PZ2: Pose files
RSR: Thumbnail files used in the Library for older versions of Poser. The newer versions of Poser use PNG image files, but some older content uses the RSR files which causes a "shrugging man" icon to appear. When this happens you'll need to use a RSR to PNG conversion software to create a new thumbnail image. This is common with older 3D content.
Diffuse Color: The primary color for an object. This is the first place you want to go when you want to change the material color of a 3D model or shader.
Highlights: Controls the highlights found on a material. These are areas on the material where the majority of the light reflects into the camera. Examples include light reflecting off glass, metal, and other shiny materials.
Ambient: Simulates the overal lighting condition in the environment. Ambient settings make cam make objects appear self illuminating. In Poser Pro 2012 and in some earlier versions, increaseing the ambient value settings will cause the object to give off light. The light that is given off isn't enough to light a room but it works well for creating glowing power cables.
Poke-Throughs (Poke Trhoughs): Happens when the skin is poking through the clothing. This happens when the body shape or pose goes beyond the limits of the clothing. People who don't have Poser Pro 2014 complain about this often. Poser Pro 2014 addresses this issue and actually has tools that specifically fit Poke-through issues.
Texture Filtering: Helps to soften jagged outlines or aliasing in an image
Raytrace Bounces: Sets the limit on how many bounces each ray of light is traced through. Higher values create more realistic reflections and refractions.
Minimum Shading Rate: The smaller this setting is here the crisper the details will be, but it will also increase rendering time.
Pixel Samples: Higher Pixel Sample values produce smoother images but increases rendering time.
Maximum Bucket Size: This determines that area of pixels that are rendered at a single time. A larger Maximum Bucket Size will speed up rendering but also uses a great deal of CPU processing.
Render Over: Specifies the background to use when rendering
Aliasing (jaggies): Appear as rough, pixilated edges on an object that is supposed to be smooth. Often gives the look of stair steps on the edges of an image. Anti-aliased is often used to correct this issue.
DPI (Dots Per Inch): This is a term that is associated with printing while PPI (Pixels Per Inch) is used when working with graphics on a monitor. DPI and PPI are often used in a similar manner, but in the world of printing you will only see DPI because it refers to how many dots the printer can print. The DPI /PPI for the image can be set in the Render Settions under Resolution. Web graphics can remain at 72 PPI which keeps the image of quality, however depending on your printing project, your resolution may need to be increased. If your printer says that the image must be at 300 DPI then simply change the resolution of the poser render to 300. To keep being confused, PPI is used when talking about monitors and DPI is used when talking about printing.
Smooth Polygons: Smoothes the objects being used. Use this to help make your tires and other round objects look smoother. Poser Pro 2014 has subdivision which also pefroms a similar function but better.
Use Displacement Maps: Enables Displacement Mapping. Helps to keep materials with displacement maps from looking flat.
Depth of Field: Creates varying focus effects where objects in the distant background are blurred. Settings for this are found under the parameters tab and under the rendering settings.
Post Filter Size: This smoothes or antialiases your render. Increasing the filter sizes increased the amount of smoothing however too large of a size will cause blurring.
Post Filter Type: This tells Poser how to antialias the render.