The D-Power is the digivice that the Tamers use in the third season of Digimon. It has many capliblities such as a card slashing function inwhich Tamers can "Digi Modify" their Digimon. Digi Modifying adds extra capabilities to that Tamer's Digimon by using one of their Digimon Cards they collect. If the Tamer believes hard enough, the card could change to a Blue Card, allowing the Tamer's Digimon to Digivolve! It can also find thier digimon too, just like in the very first episode when Takato had to find Guilmon after he was born. The Digivice is the key to Digivolution, Matrix Digivolution, and Biomerging.
If the Tamers discovered a new digimon they had never seen before, their D-Powers would show them a hologram over the digivice's screen telling them about the Digimon they have encountered.