URL
Path to the image source file.
You can change the image displayed by clicking the Browse button in the Image Properties dialog box to select a new source file or URL. All other image properties except size remain unchanged for the new image.
If the image is located on an external server, you must use the full absolute path (i.e., http://example.com/image1.jpg). If the image is located on the same server as your document, you can use a relative URL (i.e., /images/image2.jpg).
Target
Determines the window the assigned link opens after clicking the image. You can choose between New Window (_blank), Topmost Window (_top), Same Window (_self), or Parent Window (_parent).
Note: If you want to edit an image that is connected to a link, use the context menu and choose the Image Properties option. The Image Properties window will let you modify both the image and the link that it is pointing to. If you double click such image instead, you will open the Link dialog that will only allow you to edit the link properties and not the image itself.