Web Parts are the fundamental building blocks for Share Point user interface, and with them we can build and integrate many different types of applications. Web Parts are smallest component in SharePoint. Web parts are used to give more functionality to the page. In SharePoint we have custom web part as well as ready made 3rd party web part. You can create a custom web part by using visual studio.Various web parts available in SharePoint web part gallery are: Data view web part, Content editor web part, Form web part, Excel web access web part, Image web part etc.