Wonderful whippets
Whippets are the smaller cousins (19-22") of greyhounds.  Their place in the hunt is to  "course" small game such as rabbits.   Thus, they were bred for incredible speed and ability to focus. Whippets are raced for sport to this day.

At home, whippets are known for their gentle nature.   They may bark when excited, but they are not especially territorial and make gentle, quiet companions.  They'll want to accompany you on trips, but generally speaking are sensitive to change and thrive on routine. 
Whippets also tend towards solitude.  Although they are happy with other dogs, they need time with their people. Your whippet will bask and flourish in the limelight of casual life and attention.  They're not "velcro-dogs" but they'd love to stay near and watch over you.
 
Should I buy a whippet?
Whippets are serene family members, eager for the occasional run and delighted to join you for a walk or jog. They are short-haired (low maintenance), compact, and clean (they lick themselves clean!), serene and alert, and best of all, whippets are stable and trustworthy.

Reality check
Whippets are not for you if you want a heavy-duty dog.  Their skin is thin and will rip if they play too hard (we're talking running into barbed wire or dashing at full tilt through thick underbrush).