technically, it's a revocable right to use, meaning the land the flat is sitting on belongs to the authorities (freehold to them) and each flat is on leasehold to buyers for 99 years. instead of an iru (irrevocable rights of use), hdb can revoke the lease and or give excuses to force you to sell or upgrade, such as in an enbloc or enhancement scheme. overall, this is great when sinkies are impoverished, poor and starting to contribute to the local economy when jobs become available for sources of income. but when sinkies become more sophisticated, better educated, work in better jobs, have higher incomes, and start surfing and trolling the web (thanks to the pap), they becum more cynical, demanding, and behave like spoilt brats, wanting the cake and eat it too. the foundational "evil" necessities such as public housing that brought sg from 3rd world to 1st get challenged and questioned passionately.