Mathematica provides many options for styling the cells that appear in notebooks. Some of the more common styling options are available directly from the Format menu. All styling options can be accessed interactively from the Option Inspector, as well as programming through Style and related functions. Note that style options for contents of cells can also be specified at the level of complete cells.
Option Inspector — interactively set any cell styling option
Background — background color for a cell
CellFrame — whether to put a frame around a cell
CellDingbat — a dingbat to emphasize a cell
CellMargins — margins on each side of a cell