One method of customizing SharePoint, in a way that can be reused throughout the site or site collection or even the whole farm, is to create Site Columns and Content Types. Site columns are the simplest element; they are essentially the
same as list and library columns except that you create them at the site level and then they can be used throughout that site and any child site. Content Types are a combination of Site Columns as well as additional settings
and information such as document templates and workflows. Content Types, once created, can then be linked to lists and libraries.