Bitcoins have a finite supply, which makes them scarce. The total amount that will ever be issued is 21 million. The number of bitcoins generated per block is decreased 50% every four years. This is called “halving.” The final halving will take place in the year 2140.
Refers to reducing the mining reward every 210,000 blocks (approximately every 4 years). From the genesis block to block 209999 in December 2012, the reward was 50 BTC. From then until 2016 the reward will be 25 BTC, and so on until 1 satoshi will be rewarded in the year 2140. After that point no more bitcoins will ever be created. Due to reward halving, the total supply of bitcoins is finite; only about 2100 trillion satoshis will ever be created.
Malone, J.A (2015). Glossary of Bitcoin Terms and Definitions. United States: Lulu Press, Inc