A TF card stands for a TransFlash card, the name the company Sandisk originally used for its micro secure digital (SD) cards. Micro SD cards are miniature versions of secure digital cards.
Micro SD cards are currently the smallest flash memory cards available. They are most frequently found in smartphones, though many tablets and some MP3 players also use them. They work the same way as a full size SD card.
SanDisk was the first company to sell the TF/micro SD card. The cards became available in 2005 in 32, 64 and 128 MB capacities. They are now available at up to 128 GB.
SanDisk adopted the name micro SD card when the SD Card Association (SDA) began using the cards.