Flipping domain can be considered as having any kind of commodity which has a certain value
This value will increase over time
The catch is , as like any other commodity , we have to foresee that the certain commodity in possession have a certain value and will increase in value over time.Same goes for domain names
If u see a domain name at a price today and you feel that in near future the value of the name of this domain will increase one should buy it and keep it and when the individual feels the price is right then sell it in a profit.
Like real estate, like share, like cryptocurrency and many many more commodities.
In simple words buy a domain name in cheaper price and sell it in profit.Is domain flipping
There are lots of site which , foresee an estimated value of a domain, which can be a initial step to buy a domain