In 1957, The World Intellectual Property (WIPO)  set up the Nice Classification (NCL). This system groups goods and services together using a single classification scheme. Since the agreement covers trademarks registered in several different languages, the system facilitates searches for marks that may need translation. NCL separates business activity into 45 classes: 34 for products and 11 for services.
There is a detailed taxonomy or tree-like listing of goods and services, compiled by the European Union Intellectual Property Office (EUIPO), within each class that further differentiates categories. These entries provide greater detail but are non-binding categories. Since the use of this classification scheme is widespread and complicated, seeking professional help to conduct a trademark search is well-worth considering.  USPTO and most countries worldwide have adopted the NCL protocol.
The Classification Agreement lists over 10,000 goods and 1,000 services. A new edition is published every five years and a new version of each edition is published annually. Trademark offices of countries who have adopted this agreement must include the NCL codes in their official documents.
You can find your class number using our Trademark Class search engine.
http://www.wipo.int/classifications/nice/en/faq.html