In English, we use capitals in the following situations:
- At the beginning of a sentence.
- For proper names (Deborah Brody lives in Maryland)
- For titles (President Barack Obama)
We do not use capitals as a way to emphasize words, or make them prominent. For that purpose, we might underline, italicize or bold the word in question.
All caps as in NO WAY AM I GOING OUTSIDE TODAY is generally used to denote excitement, anger or “shouting.”
However, I see words being capitalized that don’t need to be, all the time.
Notice this help wanted ad from Craigslist (words underlined for emphasis by me):
Our Firm has an immediate open for two Writers/Proofreaders
We are very flexible:
You can work as contractors, Part Timers or Freelancers
You can work from your house/office or/and our office
You must have experience writing for Finance, Tax, Accounting, and Insurance businesses
You must have experience in Marketing, Advertising and Sale
You must be available to start next week
You must include your desired pay (per page and/or per hour) in your email or cover letter
This is a help-wanted ad for a proofreader! I am not sure the ad is intended to be a test or if it is showing (unwittingly) a desperate need for a proofreader.