This is a feature that is part of the code of Bitcoin. As a certain number of blocks are created, the coins created per block is reduced by 50%. This typically happens every 4 years.
Here is where Bitcoin is termed as deflationary since the inflation rate (the amount of coins produced per block) keeps being reduced.
Other applications are known to integrate halving mechanism into their protocols.
For example, Polycub has a monthly halving of its token, $POLYCUB, in an effort to make it disinflationary.
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