Blend is a compound object made by progressively changing one object into another. A blend object consists of two or more objects, between which are a number of intermediate steps in the change from one end object to the other. You can control the number of intermediate steps. In Xara LX the in-between steps are created as they are needed - they do not take up memory space in the document. For more details on using blends, see the Blends Overview.
Blends can be used to create complex highlights, blurred edges on objects, repetitive patterns and many other effects. In many ways a blend behaves like a group as it can be moved and copied like a group and you can use select-inside to select the end objects and edit them while they are inside the blend.