There's I think supposed to only ever be 21 million bitcoin. Bitcoin rewards for mining halve every ~4 years. Eventually they will stop; there will be no new bitcoin.
People will also lose bitcoin; this already happens. Famously, no one knows where ~1m bitcoin supposedly mined by Satoshi are, they are assumed to be permanently out of circulation. So not only is there a cap on maximum bitcoin, and over time less new bitcoin will be injected into circulation, existing bitcoin will also be removed from circulation over time.
This presents a strong incentive to hold bitcoin instead of spending it, since scarce assets become more valuable with increased scarcity. If a bitcoin is likely to be worth more tomorrow than it is today, you're less likely to spend it. Which has the compound effect of reducing bitcoin in circulation further.
There's I think supposed to only ever be 21 million bitcoin. Bitcoin rewards for mining halve every ~4 years. Eventually they will stop; there will be no new bitcoin.
People will also lose bitcoin; this already happens. Famously, no one knows where ~1m bitcoin supposedly mined by Satoshi are, they are assumed to be permanently out of circulation. So not only is there a cap on maximum bitcoin, and over time less new bitcoin will be injected into circulation, existing bitcoin will also be removed from circulation over time.
This presents a strong incentive to hold bitcoin instead of spending it, since scarce assets become more valuable with increased scarcity. If a bitcoin is likely to be worth more tomorrow than it is today, you're less likely to spend it. Which has the compound effect of reducing bitcoin in circulation further.
This is why people say it's deflationary.