Welcome Screen opens the Welcome Screen, which appears by default each time you start Mathematica.

Why the Coloring? opens a dialog that explains any syntax coloring in the active notebook.

Word Wrapping opens a submenu of word wrapping styles

Wrap at Paper Width wraps lines at the width of the paper currently specified by the print settings.

Wrap at Window Width wraps lines at the width of the window containing the text.

AnimationRunning is an option to Animate and related functions that specifies whether the animation they create is running.

AutoOpenNotebooks is a global option that specifies which notebooks should be automatically opened when Mathematica is started.

AutoOpenPalettes is a global option that specifies the palettes that are automatically opened when Mathematica is started.

Back is a symbol that represents the back of a graphic for purposes of placement and alignment.

Backslash[x, y, ...] displays as x\[Backslash]y\[Backslash]....