Airline miles are typically obtained either during your airline's loyalty program or via the usage of credit cards which are connected with your airline of choice. These may also be called regular flier points or frequent flier miles.
Normally, if you're a part of a reward/loyalty program inside your airline then you'll receive miles for the space you fly, the sort of ticket you purchased or the cost of this ticket. You can find the best way to earn airline miles via various online sources.
Image Source: Google
In terms of the latter method when you've got a credit card using a business connected with your airline subsequently some purchases you make through it's going to also provide you a bit of airline miles. A small proportion of your cost will be transformed into airline miles that will be deposited to your account.
In essence when you've got a credit card that's connected with your airline then you are going to be earning miles annually long in your own daily purchases that are regular. These points or miles may later be redeemed afterwards but it's well worth pointing out that these miles are not just miles from the literal sense.
If on a normal trip you obtain 500 miles which does not mean that you can use these to cover a flight which has a distance of 500 miles. Their real worth therefore differs but with sufficient miles you'll be able to redeem them for real tickets, first class tickets, quick bookings etc.