Bitcoin is a digital and global money system (currency). It allows people to send or receive money across the internet, even to someone they don't know or don't trust. Money can be exchanged without being linked to a real identity. The mathematical field of cryptography[the art of writing or solving codes] is the basis for Bitcoin's security based on Blockchain Technology.OR
Bitcoin is the currency of the Internet: a distributed, worldwide, decentralized digital money. Unlike traditional currencies such as dollars, bitcoins are issued and managed without any central authority whatsoever: there is no government, company, or bank in charge of Bitcoin. As such, it is more resistant to wild inflation and corrupt banks. With Bitcoin, you can be your own bank.
Cryptography or cryptology is the practice and study of techniques for secure communication in the presence of third parties called adversaries.
New bitcoins are generated by a competitive and decentralized process called "mining". This process involves that individuals are rewarded by the network for their services. Bitcoin miners are processing transactions and securing the network using specialized hardware and are collecting new bitcoins in exchange.