A content type is a reusable collection of metadata (columns), workflow, behavior, and other settings for a category of items or documents in a Microsoft SharePoint list or document library. Define the attributes of the particular list or library. A content type is a reusable collection of settings you want to apply to a certain category of content.

• The columns (metadata) that you want to assign to the type.
• The document template that you want to apply to new items (available for document content types only).
• Custom New, Edit, and Display forms.
• Workflows for items of the content type.
• Custom solutions or features.
• Information management policies.
• Document Information Panels, which you can then use in compatible Microsoft Office programs.
• The document conversions for items of the content type (available for document content types only).

• Discussion Board
• Announcements
• Event Calendar
• Issue Tracker
• Photo Gallery
• Asset Library
• Link List
• Tasks
• Survey
• System Page
• Item
• Video
• Document
• System
• WebPart Page
• Page Layout

Go to the  sharepoint site and   click on Settings Link. Go to the  sharepoint site and   click on Settings Link Click on Create In the Name and Description section, type a name and optionally a description for the new site content type.In the Select parent content type from list, If it is list then select item.If we want use Existing group select the group other wise we can create New Group.Click on Ok This is our Content type ,By Default item Will Come.If we want to create column