If news stories were written like the resumes I see every day, a news story about a fire might look like this:
“There was a fire on Tuesday in a building. Traffic was backed up some distance for some period of time. Costs of the damage were estimated. There may have been fatalities and injuries, or maybe not.”
Now look at your resume. Does it have bullet items like “Wrote web apps in Ruby”? That’s just about as barely informative as my hypothetical news story above. However, your resume’s job is to get you an interview by providing compelling details in your work history.
Add details! What sort of web apps? What did they do? Did they drive company revenue? How many users used them? How big were these apps?
Or maybe you have a bullet point of “provided help desk support.” How many users did you support? How many incidents per day/week? What sorts of problems? Were they geographically close, or remote? What OSes did you support? What apps? Was there sort of service level agreement you had to hit?
If you don’t provide these details, the reader is left to make her own assumptions. “Help desk support” might mean something as basically as handling two phone calls a day for basic “I can’t get the Google to work” questions. Without details you provide, that’s the picture the reader is free to infer.
When you write about your work experiences, you have a picture in your head of the history and skills you’re talking about. To you, “wrote web apps in Ruby” or “provided help desk support” brings back the memory of what that entailed. The reader doesn’t have access to your memory. That’s why you have a resume with written words. You have to spell it out, to draw that picture for her. Your details make that happen and increase the chances you’ll get an interview.