Transformers

Transformers are toy robots with the ability to transform into an alternate form, usually a vehicle or animal. The brand began in 1984 as a rebranding of Takara's dying Diaclone line. The line was extremely successful and has become one of Hasbro's flagship brands.

Transformers are quite popular on /toy/ and regularly gets threads made about them.

History
Transformers began in 1984, with Hasbro importing several toys from Takara's Diaclone and Micro Change toylines and altering them to fit the American market. Both of these Takara lines were direct spin-offs of Microman, as evident by the telltale metallic-headed pilots/riders each line had.

Most G1 Transformers have a functional cockpit because they came from the Diaclone line, which included small Microman-esque pilots that could fit inside. Many Diaclone toys had spring-loaded fists as well, allowing them to fire these off to perform a typical Super Robot style "Rocket Punch".

Micro Change, on the other hand, used a completely different scale. Rather than scaling with tiny pilots, Micro Change toys, like normal Microman figures, were meant to be 1/1 scale. Most of these Micro Change bots transformed into role play items such as a tape deck, a microscope, a pistol, or toy cars.

Most (if not all) pre-'86 movie toys came from Diaclone and Micro Change. After that, original molds were designed. Notable toys from Diaclone included Optimus Prime, Ultra Magnus, the Autobot cars (jazz, prowl, sideswipe, etc.), the Dinobots, Insecticons, and the Decepticon jets (starscream and his repaints). Micro Change included several of the Minibots (bumblebee, gears, brawn), Soundwave, Blaster, Megatron, Perceptor, and the minicassettes.

Transformers by Line
Generation 1/G1 (Retroactive nomenclature) (1984-1993)

* The old guys. When you ask your dad what Transformers are what he thinks of. For most the things like articulation were a secondary consideration compared to the transformation itself. Typically are exorbitantly expensive for mint condition ones, but used ones depend on popularity.

Generation 2/G2 (1994-1995) Beast Wars/Beast Machines Machine Wars Robots in Disguise (2001) Armada/Energon/Cybertron/"Unicron Trilogy" Classics/Universe/Generations/etc Movie
 * Bright colors and new faction symbols in hand, the relaunch of Transformers after brand was fading. Toys were a mixture of older ones in new paint schemes and brand new ones such as the popular Laser Optimus Prime. Innovations such as balljoints and light-piping were brought into the line here.
 * Major refocus, these lines primarily focused on guys that turn into animals. Unlike previous "beastformers" in G1 such as the mechanical Dinobots and Terrorcons, Beast Wars toys were robots that transformed into organic animals- often with weird weapons such as Cheetor's "gut gun" or Dinobot's tail splitting open to reveal muscle and bone. Well regarded for attention to detail in designs and range of movement, but also one of the worst offenders of latent flaws such as chrome that flakes or plastic which breaks over time. Especially under Beast Machines was very experimental in what a Transformer looks like. Very polarizing. Had Japanese-produced lines during this era which produced more figures.
 * The "Beast Wars" series went through a few different transitional stylistic periods as well.
 * Classic-style- Organic animal, mechanical robot
 * Transmetal- Mechanical animal, robot with organic aspects
 * Transmetal 2- Biomechanical animal and robot mode
 * Minor subline while the above were happening. Mostly redecoes of older toys.
 * Shark on center stage
 * Filler line with redecoes
 * The new guys are cool
 * Relaunch which was co-developed with Hasbro and Takara, was designed as a back to basics approach which had a feeling close to the original ones in design, but often focused up gimmicks in favor of less articulation than older ones. Mixed feelings all around for these guys.
 * Armada (Micron Legend in Japan) was the first full return to regular vehicle transformers again with no beasts in the show. RID2001 had earth vehicles but had tons of beast wars repaints in the mix as well. Most altmodes are very stylized and futuristic, and utilized a "Mini-Con" gimmick. Mini-Cons were small, simple robots that could plug onto pegs on Armada toys to activate crazy gimmicks. However, many toys were heavily compromised by these gimmicks and have notoriously downgraded articulation compared to toys from the Beast Era.
 * Energon (Super Link in Japan) was a direct sequel to Armada that replaced the Mini-Con gimmick with a combination gimmick. Nearly all of the Autobots in this line could combine together into a single "Super Robot", with one forming the lower half of the robot, the other forming the upper half. These combined modes rarely looked good and like Armada, heavily crippled the toys once again for a gimmick- but their articulation was certainly a step up from Armada. The Energon Decepticons, on the other hand, did not utilize the combination gimmick, and are thus at least average Transformers due to this. The line also featured (now very dated) five-man G1-esque combiners meant to invoke Devastator, Bruticus, and Superion.
 * Cybertron (Galaxy Force in Japan) was shoehorned in as a sequel to Energon in the US, and was stand-alone in Japan. While this line still had a gimmick, Cyber Keys (Force Chips in Japan), it was far less intrusive than Armada or Energon's was. Most of the toys are generally good and have decent articulation, nice detailing, and chunky/blocky designs. The Cyber Key gimmick involved a universally sized plastic chip that could be plugged into a designated slot on any Cybertron toy to activate a spring-loaded gimmick (usually pop-out weapons).
 * A come and go line which started out in the AEC days to meet supplies. Started out as crazy redecoes but became a line focused on remaking older guys to modern standards. Quite popular with collectors, as they are a modern interpretation of classic G1 characters. The line is quite extensive, with modern updates on most early G1 characters (with a few gaps here and there), several of the old combiners, and new cassettes and Headmasters (soon to come).
 * Several iterations, and a new line for whenever a new Michael Bay Transformers movie comes out (Transformers, TF: Revenge of the Fallen, Dark of the Moon, Age of Extinction, etc.).
 * This line has very different aesthetics compared to other Transformers lines, with licensed vehicle altmodes and "realistic" robot designs, looking less like a boxy robot and more like an alien.
 * Due to designs being less blocky, it's a little harder to blend the robot and alt modes together, leading to complex transformations and the occasional shellformer.

Animated
 * A line based off of the "Transformers: Animated" cartoon
 * This line also has very distinct aesthetics from other Transformers lines. Designs are very stylized and cartoony, with unconventional proportions and very simple, sleek designs. Hasbro's designers worked with the creators of the cartoon to get the toys to transform almost exactly like they did in the cartoon.

Prime

RiD 15

Masterpiece
 * Very elaborate, very expensive line produced by Takara primarily although Hasbro does many western releases. Focus on being the ultimate version of character with licensed altmodes, making appearance as close to fiction as possible, and articulation rivaling other high-end toy robots. Often held in high esteem.

Terminology
Alt-Mode- What the robot mode can transform into, the "alternate mode". A more blanket term for "vehicle mode" or "beast mode", especially considering some Transformers such as the G1 Micro Change toys become things such as guns and tape decks.

Kibble- The stuff that hangs off of a transformer in one of the modes that serves no purpose other than being decorative. High amounts of kibble can restrict posability and articulation of a toy, and may make parts clash together when transforming it, making the process frustrating rather than fun.

Partsforming- A transformation aspect that involves parts of the robot being removed and either reattached elsewhere or set aside. This tends to exclude parts that function as weapons. Partsforming is heavily discouraged among fans as it feels like "cheating" the transformation, and also leads to these extra parts more easily lost. Partsformers have luckily disappeared almost completely through modern toy engineering, but there were many examples of them back during the G1 era. A notorious example of a partsformer are the G1 "Seeker" Jets (Starscream, Thundercracker, Ramjet, etc.). Most of the Diaclone "car robot" molds also had to have their "rocket punch" fists removed and set aside for transformation.

Combiner- A large robot made up of smaller robots. The most common setup in Transformers involves a larger robot forming the head and torso section, with smaller robots forming one limb each. The combined robot is also commonly referred to as a "gestalt"- a German word meaning "formation".

Shellforming- When a Transformer fails to "blend" the use of its robot and altmode parts together well, it tends to end up as a shellformer. The term comes from Transformers that more or less are an altmode "shell" with a folded up robot inside. Due to this, shellformers can often be annoying to transform and have heavy amounts of kibble. Many of Japan's "Beast Wars Neo" toys are guilty of this problem.

5mm port- Since the Unicron Trilogy (?), nearly all Transformers can universally share weapons, as most (if not nearly all) nowadays use 5mm holes in their hands, with 5mm posts on their weapons to let their hands grip them.

Brick- A toy with little to no articulation, "posable as a brick". This term is commonly associated with G1 toys, which rarely had more than maybe some shoulder and elbow articulation.

Scramble City- A term coined by Takara to describe early G1 combiners' universal interchangeability of their components. Most G1 combiners used a larger bot to form the torso, and smaller guys to form limbs. Most of these combiners used the same ports, and a smaller bot could be reconfigured as either arm or leg, meaning there were tons of various configurations one could use, even on a single gestalt. Playability can be taken even further by switching limbs between the different combiners. For example, one could give their G1 Bruticus a Terrorcon limb, a Stunticon limb, a Seacon limb, and a Technobot limb rather than the regular Combaticon limbs meant for Bruticus. The Energon, FOC Bruticus, and Combiner Wars/Unite Warriors gestalts all use a similar system, but are restricted to their own lines. Don't bother trying to mix an FOC Bruticus and Combiner Wars Bruticus' parts together.

Retool- Making fully original steel molds is expensive, and designing a toy is both posable and transformable is a challenge as well. Not only do Hasbro and Takara release repaints, they also make retools, which use an existing mold with some new, altered parts here and there. A retool can be as simple as a new head, or as complex as Generations Springer vs. Generations Sandstorm.