I’ve to say it again: Everything is an app, we’re all becoming app developers. These were the running gags, while we saw SharePoint 2013 and the app model for the first time and it’s true. But how does such an “app” looks like in our SharePoint? Apps are grouped and arranged under the Site Contents page in SharePoint 2013. When you open this site you see a huge list of apps containing a lot of stuff that you may know from earlier SharePoint versions such as list definitions.
Each app should provide more details, to explain the users what’s the purpose of this particular app.
There are three different presentations, that apps can use in SharePoint 2013 and that are the types of apps we’re talking about for now.
1. full page apps
Full page apps will be started from the Site Contents page in SharePoint. As their name implies, these apps are running in full screen. No SharePoint UI is visible instead you can use all the space presenting a proper UI to your user.
2. part apps
Part apps are rendered in SharePoint 2013 using the ClientWebPart class. This webpart is technically just an wrapper for an IFrame, displaying the apps HTML, grabbed from the given app url.
3.UI custom actions
The last kind of apps that you’re able to build are apps extending SharePoint by using custom actions, this is a well known concept from SharePoint 2010. Extensions may sit inside of the ribbon or some of the proven extension points of SharePoint.
Within the current developer documentation Microsoft is using the following image to describe the three different types of apps. Keep this picture in mind and you’re easily able to decide which kind of app you’ve to create to achieve customers requirements.