Advertising is one sector with upfront creativity and spontaneity, it fluctuates, changes, varies from time and to time, and is counted as the selling cost of a commodity.
Well thats in economics, but as the jobs include advertising sales reps, copywriters, advertising sales director, entry level jobs, advertising manager, executive, supervisor, publishing, account executive, assistant, analyst, content-writing, consultant, operations, and retail executive jobs, advertising job profile adhere to certain requisites.
You obviously wouldnt get an executive post right after you graduate from an advertising school, but you can start at the base level then work your way up to different levels.