Explain the four principles of effective design.

Consistency: Throughout each message,be consistent in your use of margins,typeface,type size,spacing,color,lines,and position.In most cases,you will want to be consistent from message to message as well; that way,audiences who receive multiple messages from you recognize your documents and know what to expect.
Balance: Balance is an important but sometimes subjective design issue.One document may have a formal,rigid design in which the various elements are placed in a grid pattern,whereas another may have a less formal design in which elements flow more freely across the page-and both could be in balance.Like the tone of your language,visual balance can be too formal,just right,or too informal for a given message.
Restraint: Strive for simplicity.Don't clutter your message with too many design elements,too many colors,or too many decorative touches.
Detail: Pay attention to details that affect your design and thus your message.For instance,extremely wide columns of text can be difficult to read; in many cases a better solution is to split the text into two narrower columns.