First of all, it does not mean the same as not voting.

It means the voter took the time to vote and express that he/she did not wish to vote for anyone of the above.

Like with all other options the reason for this vote isn't stated although there are theories on why someomne would vote for such option. In some (feedback related) polls it is possible to state such ie. "None of the above (please specify)."

Although I don't know how this is called in English, in my language its 'blanco stem' which translates to 'white vote' or 'blank vote'. AFAIK it is a normal option in a voting process...

Reasons for voting blanco often include to express disagreement with voting process.

Reasons to express disagreement include (taken from Wikipedia NL):

* The provided statement to vote on is explainable in various ways and therefore has to be redefined.
* The voting procedure is vague.
* Those who proposed the vote haven't fully informed the eligable voters, or have done so unclearly.
* Disagreement with ability to vote. For example, to express disagreement for specific reason to vote such as in case of referedum, or to express disagreement with the democratic voting system, or democracy in general.
* Voter does not agree with any of the options.

There are several differences between a blank vote and not casting a vote. Reasons not to vote (taken from Wikipedia NL) include

* Voter is neutral to outcome.
* Voter is indifferent about outcome, cannot decide, has not looked into the subject.
* Voter is not interested in subject to be voted about.
* Voter is not for the proposal, but has a veto and with voting against the proposal would be rejected (this happens in the Security Council, where permanent members have the right to veto).

In general, by voting blank you express that you are involved (interested) in the democratic system while by not voting you express that you aren't.

Some people want everyone to vote so the percentage of voters is higher. They only do this to justify the voting process. A person who does not wish to vote, for example because he/she hasn't looked into the particular issue, has their right to do so. They could make an uninformed vote by force because they feel they have to decide based on pression from others, but this is not a sincere casted vote.

Because I don't agree with a Plurality model I always vote blank when able to.