The other two answers are perfectly valid so far. I'd like to give some clarification on the "fahrCard" itself as well as some references.
The VBB
The VBB is the Verkerhsverbund Berlin Brandenburg, which is
the public transport authority covering the federal states of Berlin and Brandenburg – the capital area of Germany.
Source
The S-Bahn Berlin GmbH aswell as the BVG operate under their umbrella.
So, when you buy a ticket, monthly or yearly subscription, that ticket complies to the VBB tariffs and policies.
The VBB fahrCard
Benefits of the VBB-fahrCard
- Easy usability: Once on board, wave the card over the reader or present card to ticket controllers.
- Increased security: In the event of theft or loss, your chip card will be blocked immediately after you’ve made a report.
- Chip card replacement: In the event of loss, theft, or damage, you will receive a new VBB-fahrCard right away via the transportation company your subscription contract is with.
- More durable ticket: The plastic card is more durable than the previous paper card. The average life span of a chip card is about 4 years.
- Privacy protection: The VBB-fahrCard only stores data previously included on the paper ticket or customer card. Data on how often you travel will not be stored.
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Note: to my personal experience, the last cards lasted only about 2 years with light stress (bending) on them.
The card itself is valid for several years or until your subscription ends. My recent card was issued in October 2019 and on the card the printed validity period is "03/2024".
You can check your card data, validity and readability in some service centers of the Deutsche Bahn. One service center that I know is at Friedrichstraße next to the escalators near exit Friedrichstraße. It's a small terminal next to the ticket machines. Just touch the card onto the terminal.
The subscription recipe lists the data that is stored on your card and you can read the data on the card with any RFID/NFC reader app on a modern smartphone.
The data roughly includes:
- the card ID (related to your subscription)
- the tariff (VBB-Umwletkarte, for example)
- the tariff area (A/AB/ABC etc.)
- the card validity range
There's also a FAQ on their site: fahrCard FAQ
The fahrCard was introduced around 2015.
The VBB-Umweltkarte (yearly subscription)
- You can take 1 adult and 3 children with you after 8pm on weekdays and all day at weekends.
- This ticket is transferable, i.e. another person can use it.
Source
Unfortunately, I was not able to find these informations on the VBB nor on the BVG sites in English language.