First of all, let me give you a refresher about cryptocurrency with this definition from Wiki.

What is a cryptocurrency?

"A digital currency in which encryption techniques are used to regulate the generation of units of currency and verify the transfer of funds, operating independently of a central bank."
The most famous cryptocurrency nowadays is Bitcoin created by "Satoshi Nakamoto". You can learn more about bitcoin.
Where the world truly needs a reliable digital currency and infrastructure that together can deliver on the promise of “The internet of money”, Facebook has come up with the idea of launching their own cryptocurrency. The details are below.

Libra coin

Libra is permissioned blockchain digital currency introduced by Facebook. Libra coin

Libra Association

An independent group of people who are going to work together for Libra's joint purpose and will take care of Libra coins is known as the Libra Association.
Libra Core
It is the name for the implementation of the Libra protocol introduced by Libra Association.

Digital Wallet

Libra will be used through its separate wallet named Calibra Wallet. Calibra will be available as a self-driven app and also, in FB messenger and WhatsApp.

Stable coin - Libra

Libra is attached with currencies from different countries which defend Libra from fluctuation, which makes Libra consistent. The ability to be consistent is called stability and that makes Libra a stable coin.
Libra - A Future Global Currency By Facebook
  • Name - Libra.
  • Introduced by - Facebook’s LIBRA Association.
  • Mining rights to - Libra Association’s people only.
  • Property planning and development - Centralized.
  • Based at - Geneva, Switzerland.
  • Consensus algorithm - Byzantine fault tolerance.
The Libra association believes that the exchange of e-money should be safe and smooth. They have introduced a frictionless, safe, and secure way of sending and receiving assets which are even more secure way than normal messages and text are sent by.
Libra’s motto is to empower people by providing them global currency and financial infrastructure. Libra is made of three main parts which will work as a coupled financial system.
  1. It is built on a trusted, secure, and scalable blockchain.
  2. It is backed by a reserve of assets designed to give it intrinsic value.
  3. It is governed by Libra Association.
It is built on “Libra Blockchain.” Talking about acceptance of Libra, the Libra association states that everyone has to trust a new trend of crypto called Libra and people need to have confidence that Libra will be a good choice for them as it secure and governed by semi-governance(Libra Association), and accepted by the government of UK central banks.
To have a stand in the digital currency market Libra will need partners companies which will push it and encourage people to use Libra as a global digital currency. The initial group of Libra consists of companies classified as below,
    1. Mastercard
    2. Mercado Pago
    3. PayPal
    4. PayU
    5. Stripe
    6. Visa
    1. Booking Holdings
    2. eBay
    3. Facebook/Calibral
    4. Farfetch
    5. Lyft
    6. Spotify AB
    7. Uber Technologies
    8. Inc
    1. Iliad
    2. Vodafone Group
    1. Anchorage
    2. Bison Trails
    3. Coinbase
    4. Xapo Holdings Limited
    1. Andreessen Horowitz
    2. Breakthrough Initiatives
    3. Ribbit Capital
    4. Thrive Capital
    5. Union Square Ventures
    1. Creative Destruction Lab,
    2. Kiva
    3. Mercy Corps
    4. Women’s World Banking
The architecture of Libra will have,
  1. Move, a new programming language.
  2. Byzantine Fault Tolerant (BFT) consensus approach.
  3. Adopted blockchain data structures.

Bitcoin vs Libra

Bitcoin Libra
1)Bitcoin decentralized cryptocurrency. 1)Libra will centralized digital currency.
2)Bitcoin is not controlled by any entity. 2)Libra will be controlled by Libra Association.
3)The limit of availability of Bitcoin is 21 Million. 3) Libra is endless and subjected to the demand.
4)Bitcoin’s price is independent, it can vary. 4)According to whitepaper price of Libra is depended on leading national currencies.
5)It is running over permission-less blockchain so anyone can do mining. 5) It will run of permissioned blockchain so miners have to take permission from Libra Association.

Why Libra

References and learn more
For more details, you can go through the following.