To enter New Zealand you either need a Visa or be from a Visa Free Country or be exempt from needing a Visa.

Visa Free Countries

Short visits
If you are visiting for three months or less and are from a country in the list below, you will not need a visa.
Andorra, Argentina, Austria, Bahrain, Belguim, Brazil, Brunei, Bulgaria, Canada, Chile, Cyprus, Czech Republic, Denmark, Estonia*, Finland, France, Germany, Greece, Hong Kong**, Hungary, Iceland, Ireland, Israel***, Italy, Japan, Korea (South), Kuwait, Latvia*, Liechtenstein, Lithuania*, Luxembourg, Malaysia, Malta, Mexico, Monaco, Netherlands, Norway, Oman, Poland, Portugal****, Qatar, Romania, San Marino, Saudi Arabia, Singapore, Slovak Republic, Slovenia, South Africa, Spain, Sweden, Switzerland, United Arab Emirates, United States of America, Uruguay, Vatican City

Australian citizens and holders of a current resident return visa issued by the Commonwealth of Australia do not need a visa.

A Visa is a label that is issued by a New Zealand Immigration Branch before entering New Zealand.
To work, study or set up a business in New Zealand you need to be issued a Visa.
To gain a Visa in New Zealand, applicants need to meet strict Health, Charactor and English Language requirements.

The main categories of Visas in New Zealand are;
Work Visa which entitles the bearer to work in New Zealand, usually for a set period of time of 1 year or 2 years.
Residence Visa which entitles the bearer to reside in New Zealand and enjoy the same benefits as a New Zealand citizen.
Study Visa which entitles the bearer to undertake a course of study in New Zealand which usually is paid for before the course starts and can allow the bearer to work up to 20 hours a week in New Zealand
Entreprenuer Work Visa (EV) which entitles the bearer to gain entry to New Zealand with the undertaking that they will set up a business that will benefit New Zealand as a whole.
Investor Category 1 and 2 are where the bearer has transferred a set amount of funds to New Zealand that remains as an acceptable investment.
Both the EV and Investor categories require significant funds, business experience and knowledge to be successful.