Snaps
The types of snaps are:
Sketch Snaps and Quick Snaps are related, but not identical. Sketch Snaps are global sketch settings that apply to all sketch commands. Quick Snaps are single, independent selections.
Sketch Snaps
Each Sketch Snap allows you to automatically snap to selected entities as you sketch. By default, all Sketch Snaps except Grid are enabled. You can control all Sketch Snaps through snap options.
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Access Sketch Snaps through the Quick Snaps toolbar, the Quick Snaps 
flyout on the Sketch toolbar, or the shortcut menu.
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Use Sketch Snaps with sketch entities, model edges in parts, assemblies, and drawings.
On sketches with multiple entities, only the current sketch entity displays snaps.
To wake up Sketch Snaps:
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Create any sketch with multiple entities.
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With any sketch tool selected, hover the pointer over a sketched entity.
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The sketch entity changes color.
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The appropriate Quick Snaps appear on the sketch entity.
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The pointer changes, adding the appropriate inference information.
Quick Snaps
Quick Snaps are instantaneous, single operation Sketch Snaps. For example, sketching a line from start to finish is a single operation. You can double-click any Quick Snaps on the toolbar to retain the snap capability for multiple instances of the same sketch entity, or until you select a different Quick Snaps.