Until the mid 1980s, nearly all electronic components were “through-hole components” with legs spaced 0.1″ apart to insert through the circuit board and then be connected with traces on the back. But to make ever smaller circuits possible, the vast majority or chips, resistors, capacitors, etc. are now made to one of the much tinier surface-mount-technology (SMT) specifications. These components are designed to be placed onto circuit boards by machine, but with the larger versions, it is still possible to solder them by hand.
I met Adam Wolf & Matthew Becker of Wayne & Lane at MakerFaire 2013 and bought their “I Can Solder SMT Blinky Grid” kit. It was fun to assemble and runs perfectly nearly a decade later. It also has a very clever method of programming the output: Enter the text on their website and hold the device up to the website screen. It flashes on-and-off for thirty seconds and the photo-resistors on the board react to the light and re-program the display message.