Spacers and standoffs can be crucial in achieving both improved aesthetics and proper functioning of certain devices and products, including avoiding short-circuiting of powered components (such as computer motherboards) by creating a small air gap between the powered component and any metal housing it's installed into.
A spacer is a small piece of material - generally metal or plastic - that sits under the head of a screw or bolt but on top of the surface being screwed into, rather like a more elongated version of a standard washer.
A standoff is a similar component to a spacer in many ways, with the key difference being that standoffs tend to be threaded onto the screw and/or the surface they're being installed on.
A swaged standoff is one that has both internal and external threading cut with a swage tool, creating an end which resembles a male exterior but that retains internal (female) threading, allowing for tighter grip on both male and female fasteners and anchor points.