SkyMiles is the loyalty program of Delta Airlines, a major US airline. You can register for free here.
There are several ways to earn SkyMiles.
Your SkyMiles do not expire and can be used to purchase:
Medallion status is divided into four levels:
Silver, Gold, Platinum and Diamond. They provide upgrades, qualifying miles, priority boarding, free baggage, access to lounges and other benefits to enhance the flying experience.
You can register online on the Delta website.
Every dollar spent at Delta earns 5 SkyMiles points. However, point gains vary depending on the air partners.