Tech Specs (short for "technical specifications,") are the character-ratings that many Transformers have received on their packaging or on Hasbro.com, ranking qualities like "Strength" and "Intelligence" and "Skill" on a scale of 1-10. While technically the character bios included on most toys are separate from the Tech Specs - and are sometimes called out as such on the packaging itself - the graphic design traditionally merged them into a single box/card (which you are encouraged to "clip and save!"), along with a reduced version of the character's package art. Thus, "tech specs" has become, in casual use, a shorthand term for the entire bio/art/Tech-Specs combination.
The current lineup of stats is: Strength, Intelligence, Speed, Endurance, Rank, Courage, Fireblast (previously Firepower, which actually means something), and Skill. This list has varied surprisingly little over the decades.
While these stats often correspond at least loosely to the described abilities of the characters, parity between characters is virtually nonexistent. Optimus Prime, for instance, has traditionally maxed out most or all of his stats, despite the existence of much stronger, faster, fireblastier characters. The only category with anything really close to a sense of scale between characters is "Rank," where faction leaders tend to be 10s, group leaders tend to be 9s and 8s, and most others are below that. There are of course many exceptions, but at least there's a solid trend.
Tech Specs were present right from the start. With the very first Transformers also came a packaging gimmick: Kids were instructed to "use the special decoder inside to decipher your Tech Specs." A fuchsia criss-cross pattern obscured the blue line that indicated the various ratings, so overlaying a piece of clear red plastic made the blue line much easier to see.
This design was used for a number of years, but it was eventually dropped just before the end of G1 and has yet to return.
However, the Tech Specs tradition far outlasted the "decoder" gimmick. In fact, it once had even spread beyond the packaging and onto the toys themselves. The Headmaster figures contained abbreviated Tech Specs bar-graphs inside their chests. When the head was plugged into the body, bars would emerge on the graph.
After the cartoon was canceled and the comic entered the Furman years, many new toys were made whose corresponding characters never appeared in the fiction. But, with an extremely small number of exceptions, Hasbro continued writing bios and Tech Specs for every toy, and this was the only source of "life" for dozens - perhaps even hundreds - of characters. While some European toys were released with virtually no character information (not even names), even this was a small hiccup in the larger trend.
The Micromaster patrols were notable for being the first variation in stat categories, replacing "Rank" with Teamwork and "Firepower" with Cooperation. The difference between Teamwork and Cooperation isn't quite clear.
The early Generation 2 packages kept all the same information as the Generation One toys before them but reorganized it, placing the portrait and bio sections above the stats so that the whole thing resembled a trading card.
Some later Generation 2 toys took this further and came with a separate tech spec card that could fold over so as to "pop-up" an image of the character.
Beast Wars kept the "trading card" layout but rearranged the elements again. For the first time, the stats were represented numerically rather than via a chart. The portrait was also enlarged.
Earlier cards also included a space displaying the toy's hidden weapons.
Beast Machines altered the tech spec format once again, most obviously by replacing the illustrated portrait that had been included since Generation One with a picture of the actual toy.
More subtly, Beast Machines might be seen as foreshadowing the Robots in Disguise line by beginning the disintegration of the "trading card" format that had predominated in G2 and Beast Wars. While some of the figures did arrange the Tech Spec info in a roughly card-shaped format, it was looser and less formalized in organization. The lack of a standardized size, shape, or backing made them seem less like distinct collectible cards and more like... well, just bits of the box you might want to keep.
It was RID that marked the first real break in tradition, brought on by a move to trilingual packaging. Toys on the smallest packaging cards, such as the Spychangers, literally did not have room for character information. Most Deluxe-sized and larger packaging still retained bios, Tech Specs, and "art," but the bios were graphically separated from the "clip-and-save" box that contained the rest. In at least one case, creative use of space put the Tech Specs box at a 90-degree angle to the rest of the layout, including the bios. And in another, there was no bio at all.
Later on, individually-carded Kay-Bee and Target exclusive versions of the six show-character Spychangers were released with bios and Tech Specs, since the exclusive packaging was English-only. However, this didn't last; the final RID exclusives had Armada-style trilingual packaging with no character info except for names and allegiances. All told, a little less than half of RID releases lacked bios and Tech Specs, which meant more than a third of the characters.
Armada continued the departure from tradition, eliminating all character information from the packaging beyond names, allegiances, and a few trilingual "blurbs" noting the vehicle modes and conspicuous weapons or gimmicks. The toys came with sticker cards that had their pictures and names on them, but no further information. This was also true for the Universe line, which started halfway through Armada's run.
Some bios and Tech Specs did appear, but only on the Hasbro website, only for the main Armada characters, and only on a somewhat haphazard schedule. The fandom response ran from neutral to negative; certainly no one was happy about the dwindling output, especially since the supplementary character info had had the most impact on characters who had no other fiction.
But by the time of Energon, the in-package stickers had become trading cards, and in response to the fandom, each had Tech Specs on the back. However, the casual use of the term had muddied the issue: In granting the request for "tech specs," Hasbro hadn't realized that the most important part was the bio, not the actual Tech Spec ratings. So some more time passed before packs of trading cards with bios were released. And, of course, bios continued appearing on the Hasbro site for Energon and Universe characters, though not every character in those series got in before the practice was discontinued.
It was with Cybertron that bios and Tech Specs finally returned to the packaging, with even more information (sometimes further bio info, sometimes toy-trivia) hosted online and accessed via Cyber Key Codes. The Tech Specs also introduced unknown as a rating, such as for Galvatron's stats.
As part of the processing performed at Axiom Nexus by the Transtech, each offworlder is given an identification which includes among other things, their tech specs. Hubcap did not know what to think about "Strength - 3". At one point he told a security official "check our tech specs".
When Hasbro went to trilingual packaging, Aaron Archer said it was because they believed in the near future all products, down to mundane items such as sticks of butter, would require it; they were attempting to get "ahead of the curve." Five years later this obviously has not come to pass, to the relief of most Transformers fans, but not necessarily everyone.