The Digimon franchise is all about the bond between the titular Digital Monsters and the humans (also known as the DigiDestined) that they're bonded to. These relationships manifest in different ways, but they're key to the main Digimon achieving their strongest forms. There are also iconic items seen in the classic Digimon Adventure continuity that tie into such transformations.

Crests and Tags are vital to the DigiDestined in many ways, at least in the original Digimon Adventure anime. Representing the concepts and morals that they each embody, Crests and Tags allow the user to wield special powers and abilities. More importantly, however, they trigger the ultimate Digivolution for their respective Digimon, meaning that these forms can only be accessed once the Crests and Tags are activated.

Crests/Tags appeared in the original Digimon Adventure anime, its sequels (Digimon Adventure 02, Digimon Adventure tri and Digimon Adventure: Last Evolution Kizuna) and the 2020 Digimon Adventure remake. The Crests represent different elements or concepts tied to each of the DigiDestined, and they're comprised of symbols on small tablets. Crests also have corresponding Tags that they slide into, with said Tags usually being worn around the necks of the DigiDestined. Whenever the traits of a Crests are exhibited by their personal actions, they'll begin to glow, allowing the person in question to evolve their Digimon from Champion level to Ultimate level. For instance, Tai uses his Crest to digivolve Greymon into MetaGreymon.

Crests and Tags can also be used to attempt to "warp digivolve" a Digimon to a far higher form, though this doesn't always work. Tai attempted to turn Agumon into another form while the Crest was corrupted, causing a "dark digivolution." As a result, Agumon instead turned into the monstrous SkullGreymon. The Crests were once stolen by Piedmon and subsequently hidden away across the Digimon World by Devimon. For this reason, the DigiDestined had to find their Crests as they make their way through the digital environment, with Tai's Crest of Courage (the first Crest found in the series) located randomly in a cave.

Despite how important they initially seem in terms of triggering digivolution, Crests aren't the true reason for this. They, along with their Tags, are proven to merely be "focus points" for them to concentrate on, with the actual power having always been within their hearts. Even after they lose the powers that were once inherent to the Crests and Tags in the second season of Digimon, the DigiDestined later regain them upon being given a DigiCore. It's worth noting that the kids lost the ability to use their Crests whenever they went against the concepts that they represented. This is seen when Matt and Gabumon have issues with their bond/partnership. The latter finds that Matt's Crest doesn't glow anymore, while Gabumon is unable to digivolve.

Special Powers of the DigiDestined's Crests

Though the physical items might not have truly been necessary to digivolve their partner Digimon, the DigiDestined had other uses for their Crests. This includes shooting out arrows made of light to correspond to a prophecy involving arrows, or dispelling poison that should have rendered the user unconscious. This all showcased how the Crests were specifically made for each of the kids, and they weren't merely there as happenstance. They were actually created, along with the Tags and Digivices, in a lab to be used later by each of the children. Likewise, their partner Digimon were also chosen by this point, despite the fact that these events didn't take place until 4–5 years after the fact.

Of course, the actual Crests were eventually stolen by Piedmon, with the DigiDestined having to use their Tags (which would glow if nearby) to hunt for their Crests. In later adventures, the group used their physical Crests together in order to open a Digital Gate. The fact that this was done years after they had intiially stopped relying on their Crests shows that the items have a lot of unknown or theretofore yet-to-be-revealed powers. Likewise, the kids simply thinking of this idea also means that the powers that they activate by focusing on their Crests are inherent to the children themselves. By being exposed to the Crests and Tags for so long, they have a greater idea of what they can do, even without realizing it.

The Crests of Each DigiDestined

The symbols on each of the DigiDestined's Crests corresponds with a similar emblem seen on the bodies of the Digimon from that same grouping. An example would be how the Digi-Egg of Courage, which is the sun symbol for Tai's Crest, can be seen on WarGreymon's shield. As noted, the kids have to utilize something related to the trait of their Crests in order for them to activate. Tai risked his own life when he tried to save Sora from Datamon, thereby activating the Crest of Courage. Matt realizing the extent of Joe's friendship with him activated the Crest of Friendship, while Sora standing by and helping the evolved Biyomon activated the Crest of Love. Mimi's commitment to fulfilling a promise activated the Crest of Sincerity and Izzy reclaiming his lost sense of curiosity acivated the Crest of Knowledge. Likewise, Joe rescuing a drowning Takeru (despite not knowing how to swim himself) activated the Crest of Reliability, while the reunion of T.K. and Tokomon activated the Crest of Hope.

Some of the other Crests, namely the Crest of Kindness'Two Crests – the Crest of Destiny and the Crest of Miracles – debuted in a toyline of Digimon merchandise. They were later added to the second season of the Digimon Adventure anime, with the Digi-Egg of Miracles actually created from a corrupted version of the Crest of Kindness. In both the Japanese and English version of the show, the Crest iself seems to have some level of intelligence and sentience. In the case of the Crest of Light, it's actually already held by Myotismon when the DigiDestined realize what it even is. Despite how important they were, Crests and Tags were only used in the intiial Digimon continuity, with subsequent versions of the franchise going in much different directions.The somewhat controversial Digimon Tamers was in a completely separate timeline, with the Digimon and other aspects being treated in the manner of a trading card game (just like the real-life Digimon cards).

Thus, Digivolution – including to powerful Ultimate levels – was simply a matter of cards, making Crests and similar items irrelevant. Conversely, the even more contentious Digimon Frontier was far more like a tokusatsu or superhero series than a traditional "monster raising" anime. In that series, the DigiDestined actually merged with the spirits of Digimon instead of having traditonal partner Digimon. This series' vastly different "Spirit Digivolution" was another strange change of pace, but it cemented the fact that the franchise has always been reinventing itself. Thus, Crests and Tags weren't present in other Digimon works, and they're now an old-school gimmick. For fans of the original Digimon anime series, however, key character development and other parts of the show will always be tied to Crests and Tags.