Tom: Composition is about the arrangement of the visual elements like the structure of the art of picture

Ell: typography is the art, technique or layout of arranging text to make it more appealing. Size of the font, font style or artistic style of  

Ryan: Image optimization is when an image is compressed to the most visually acceptable, image for saving memory.The power of two is when the width and height of a image is at the same value.These values are import to make sure when 3D MODELING textures fit and render properly. When the size of a texture is stretched to fit a model by the program this is called interpolation.  

thumb nail sketches

Thumbnail sketches are drawing quick, abbreviated drawings. Usually, they are done very rapidly and with no corrections - you can use any medium, though pen or pencil is the most common. Thumbnails sketches are usually very small, often only an inch or two high.

the audience is the people we are aiming the game at for example a 2D game like sonic the hedgehog would be aimed and 7+ and then the designers will build the game around the set age of the audience and set the game up so it is staged so a person in that audience can understand it.