HTML - margin

The margin property can have from one to four values.

• margin: 25px 50px 75px 100px; 
  • top margin is 25px
  • right margin is 50px
  • bottom margin is 75px
  • left margin is 100px
• margin: 25px 50px 75px;
  • top margin is 25px
  • right and left margins are 50px
  • bottom margin is 75px
• margin: 25px 50px;
  • top and bottom margins are 25px
  • right and left margins are 50px
• margin: 25px;
• all four margins are 25px

http://www.w3schools.com/css/css_margin.asp