Item types are groups of items of material in the library that are circulated in different ways.
Item types are also a very important part of Koha's circulation module.
You can find the types screen in the Patrons and Circulation section in Koha's Administration module.
Unless your library is just starting up, you will already have your list of Item types. Just like with patron categories you might consider modifying the item type list to take advantage of some of Koha's capabilities.
We will need to consider what types of material in the library have have distinct characteristics. We need to assess if types of material are different in one or more of following ways:
Renewal policies
Not for loan policies
Loan period
Maximum checkouts
Fine amount
Rental charge
Here's a good example of Koha's default Item type list:
Books
Reference
Journals
Reports
CD/DVDS