TOS: Red was security and death on away missions. Command personnel wear green(which would tend to look gold on film) Science and medical personnel wear blue Operations wear beige.

I think it represented the type of job the person had.

This is another great question, one that can be resourced all over the web, almost endlessly. I will try not to write a book here, while still adding a helpful and interesting answer.   - There were many different types and variations of Star Trek uniforms, this site explains in detail, the differences. http://memory-alpha.org/en/wiki/Starfleet_uniform   - Apparently, besides a difference in time ( production, and space time...) there is also a difference between the uniforms that were used in the shows, and the movies. I hadnt thought of that, but I do remember this now.   - Wikipedia says: The shirt color indicates crew members' branch. In the pilot episodes, command personnel wear green (which tended to look gold on film), science and medical personnel wear blue, and operations wear beige. (TOS: "The Cage", "Where No Man Has Gone Before"). When Star Trek went into regular production, the department colors were altered: command and helm personnel wear gold shirts, engineering and security personnel wear red, and science and medical personnel wear blue (TOS: "The Man Trap"). The frequent death of red-uniformed security officers led to the coining of the term redshirt. The command uniforms were in actuality green, but appeared gold on screen. http://en.wikipedia.org/wiki/Starfleet_uniforms#Television_uniforms   Then Allexperts.com says.. (This portion of an answer describes the shirt colors for "The Next Generation" ) The three uniform colors are red, gold, and blue, and they represent different departments on a starship. Red uniforms are for command and navigation, gold uniforms are for engineering, security, and operations, and blue uniforms are for science, including medicine. Although Data served as Second Officer, he wore a gold uniform since his primary position was Chief of Operations. http://en.allexperts.com/q/Star-Trek-Next-1184/Uniforms-1.htm   PERSONALLY- I dont think any of this actually answers the question, but, the answer depends on which time period of Star Trek you are talking about, and whether were talking about a movie or a tv show. Hopefully, with the links provided, we can strudy this further, with more information, and provide more specific data.