Occam's razor

Occam's razor (also Ockham's razor or Ocham's razor (Latin: novacula Occami); further known as the law of parsimony (Latin: lex parsimoniae) is the problem-solving principle that essentially states that "simpler solutions are more likely to be correct than complex ones." 

Occam's razor (or Ockham's razor) is a principle from philosophy. Suppose there exist two explanations for an occurrence. In this case the one that requires the least speculation is usually better. Another way of saying it is that the more assumptions you have to make, the more unlikely an explanation.