Smudging is use to purify the spirit and body of bad energy.  Smudging can also be used to cleanse an object or a given area of negative influences.  Sage, sweet grass, and cedar are the most often used.  Tobacco  is also used in certain circumstances.  Sage is burned  to get rid of evil spirits and negative feelings.  It is also used to create areas of protection from these energies.  During ceremonies a circular area is often protected with sage.  Cedar works both as a cleanser and an attracter of good energy.