You can combine several objects into a group so that the objects are treated as a single unit. You can then move or transform a number of objects without affecting their attributes or relative positions. For example, you might group the objects in a logo design so that you can move and scale the logo as one unit.
Grouped objects are stacked in succession on the same layer of the artwork and behind the frontmost object in the group; therefore, grouping may change the layering of objects and their stacking order on a given layer. If you select objects in different layers and then group them, the objects are grouped in the layer of the topmost selected object.
Groups can also be nested—that is, they can be grouped within other objects or groups to form larger groups. Groups appear as <Group> items in the Layers panel. You can use the Layers panel to move items in and out of groups.
Expanding objects enables you to divide a single object into multiple objects that make up its appearance. For example, if you expand a simple object, such as a circle with a solid-color fill and a stroke, the fill and the stroke each become a discrete object. If you expand more complex artwork, such as an object with a pattern fill, the pattern is divided into all of the distinct paths that created it.
You typically expand an object when you want to modify the appearance attributes and other properties of specific elements within it. In addition, expanding objects may be helpful when you want to use an object that is native to Illustrator (such as a mesh object) in a different application that doesn’t recognize the object.
Expanding is particularly helpful if you are having difficulty printing transparency effects, 3D objects, patterns, gradients, strokes, blends, flares, envelopes, or symbols.
Sets the tolerance for color values between color stops. Higher numbers help maintain a smooth color transition; low numbers can create a more banded appearance.
Hold down Alt (Windows) or Option (Mac OS) as you choose Object > Expand to expand a gradient using the settings last entered in the Expand dialog box.