Being a Share Target
Apps that are appropriate share targets are rarer than apps that are appropriate share sources. However, any app involved with publishing, storing, or transforming data—even something silly such as adding speech bubbles to photos—can be a good share target.
Being a share target is more involved than being a share source. To be able to receive content, an app must declare itself as a share target in the package manifest for specific formats and/or file types. And you must remember to do this in both package manifests if you want this functionality to work on both phones and PCs!
The easiest way to support the Share Target contract is to right-click on your project in Visual Studio, select Add, New Item..., then choose Share ...