• /opt, a directory in the Filesystem Hierarchy Standard
  Filesystem Hierarchy Standard
  The Filesystem Hierarchy Standard defines the main directories and their contents in Linux operating systems. For the most part, it is a formalization and extension of the traditional BSD filesystem hierarchy....
  
  
• Opt out, in broadcasting, when a nation or region splits from the main national output
• Opt-out
  Opt-out
  The term opt-out refers to several methods by which individuals can avoid receiving unsolicited product or service information. This ability is usually associated with direct marketing campaigns such as telemarketing, e-mail marketing, or direct mail. A list of those who have opted-out is called a...
  
  , to avoid receiving unsolicited product or service information
• Opting out
  Opting out
  Opting out is a political expression that was formulated in Canada to describe the intention of a province to remove itself from a program administered by the federal government, or to exempt itself from a constitutional amendment that would transfer its legislative powers to Parliament.Up until...
  
  , a political expression in Canada, describing the intention of a province to remove itself from a program administered by the federal government
• Opt in e-mail
  Opt in e-mail
  Opt in email is a term used when someone is given the option to receive "bulk" email, that is, email that is sent to many people at the same time. Typically, this is some sort of mailing list, newsletter, or advertising...
  
  , the option to receive bulk e-mail

• Option key
  Option key
  The Option key is a modifier key present on Apple keyboards. It is located between the Control key and Command key on a typical Mac keyboard. There are two option keys on modern Mac desktop and notebook keyboards, one on each side of the space bar....
  
  , a modifier key on Apple keyboards

• Occupied Palestinian Territory
• Optional Practical Training
  Optional Practical Training
  Optional Practical Training is a period during which undergraduate and graduate students with F-1 status who have completed or have been pursuing their degrees for more than nine months are permitted by the United States Citizenship and Immigration Services to work for at most one year on a...
  
  , a temporary employment authorization for F-1 students
• Optimized Production Technology, a production planning system created by Eliyahu M. Goldratt
  Eliyahu M. Goldratt
  Eliyahu Moshe Goldratt was an Israeli physicist who became a business management guru. He was the originator of the Optimized Production Technology, the Theory of Constraints , the Thinking Processes, Drum-Buffer-Rope, Critical Chain Project Management and other TOC derived tools.He authored...
  
  
• Population Matters, (formerly known as the Optimum Population Trust), a UK charity devoted to tackling overpopulation.

Computing