A puzzle designed to be solved without using calculators, online decoders, or computer programming. Using a computer to type and post the answer is allowed; the spirit of this tag is to make people solve the puzzle on their own.

This tag should be used for a puzzle that can be solved by brute-force calculation or programming, but where the puzzle-setter explicitly does not want people to do so and is looking for a solution that can be understood without the use of a calculator or computer. You're still allowed to use a computer to post the solution; Stack Exchange doesn't support smoke signals yet. For further discussion of exactly how much computer usage is allowed, see this meta post:

The spirit of the tag is to solve the puzzle on your own, without the aid of computers. Obviously you will need a computer for some aspects, such as typing in the solution and posting it, but the real point is that you should use your own knowledge or ingenuity. There are various ways you could use a computer for not-in-the-spirit-of-the-puzzle shortcuts:

  • programming,
  • brute-forcing possibilities,
  • using online word finders,
  • searching the web for specific strings/information,
  • etc. etc.

Depending on the puzzle and the OP's intent, any of these might be acceptable, and the tag is there to tell you that it isn't. The tag means different things in different contexts, as may be clarified by the OP in the body of the question.

Don't take the tag name too literally: it doesn't exclude things like keeping track of your progress in a text document, which could just as easily be done with pen and paper.