Dead bug prototyping and freeform electronics are a way of building working electronic circuits, by soldering the parts directly together, or through wires instead of the traditional way of using a printed circuit board (PCB.)
Dead bug prototyping got its name because when you invert a IC, and bend the legs out, it looks like a dead bug. Sometimes you can make your whole circuit work just by soldering the parts directly to an IC, and the easy way to do it is to lay the chip upside down, bend the leads out and solder parts together. Sometimes people use many chips, and glue them upside down to a blank PCB, then build the circuitry from part to part.
This type of circuit is often a quick way to get going on a project, and is a good way to test stuff, before investing in printed circuit boards, which makes it useful in prototyping, or even for building small quantities, but its fairly labor intensive, often difficult to build, and ends up looking ugly.
The neat thing about building circuits without boards is that it removes the need for everything to be on a plane, making for more interesting looking 3D circuits, rather than 2D circuits. Geometry comes more into play this way, and the way parts are manufactured, the number of leads, how they are organized all limit, and shape the way the parts can fit together. Some parts have 2 axial leads, others may have 2 or more linear leads or dual in-line leads, while another may have leads in a radial fashion. Surface mount parts and through hole parts have different properties, but they can both work fine and can even be mixed in the same designs.
When I used to work building electronics, engineers would revise designs, which would cause changes in manufacturing. We would do things like clipping a lead on a part, solder a different part on to that one, or sometimes on top of another part. It was pretty common practice to piggyback memory modules or chips to make a bigger memory module or chip. This sort of thing is practical and viable in many useful ways. Its also can be aesthetically appealing, and interesting looking.
The purpose of this instructable isnt to show you how to do this, but rather that its a fun way to build interesting electronic projects, as well as a quick way to see if your thing works.