Mifare is a 13.56 MHz contactless technology owned by NXP Philips. It complies with ISO14443A - the industry standard for contactless smart cards. Mifare cards are powered by an internal antenna as the card moves into a magnetic field. Mifare has proven popular as the card to use in ticketing and low value transactions.

operating frequency: 13.56 MHz.
read range: from about 0cm up to 10 cm.
card size: approx. 85.7mm x 54.0mm x 0.8mm.
data capacity: a standard 1K Mifare card has 16 sectors each with 4 blocks of data that are 16 bytes. Other capacities are available.

the radio transmission between the Mifare chip and the reader is encrypted.
each sector can have its own 48 bit keys for read and write access, this allows multiple applications from different vendors to operate on the same card.
access to data from each sector is protected with a 48 bit key.
the actual data stored on the card can be either encrypted or not encrypted.
each sector can be read only.