> For the complete documentation index, see [llms.txt](https://eako-capital.gitbook.io/eako-user-guide/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://eako-capital.gitbook.io/eako-user-guide/barrier-options/types-of-barriers.md).

# Types of Barriers

### American

A barrier that is continuously observed throughout the life of the option.

### Discrete

A barrier that is observed only at one or several predefined times (as opposed to continuous), typically on observable fixing pages.

### Single

Single Barrier - any barrier option with one barrier which, if hit, will Knock-In (Knock-Out) the option.  Single barrier options can be further categorised into sub-types:

Out of the money barriers - this means that the option is OTM when the barrier is hit.

In the money barriers - sometimes called reverse barrier options.  These are options that have positive intrinsic value (are ITM) when the barrier is hit.

### Double

Double Barrier - any barrier option with two barriers where, if either barrier is hit, will Knock-In (Knock-Out) the option.

### Sequential

Any barrier option with more than one barrier where one or more of the barriers can affect the option differently.  E.g., an option that can Knock-Out and/or Knock-In.  Once knocked out it can never be knocked in.  If first knocked in, it can still be knocked out later.

### Parisian

A barrier option that requires a number of events to be triggered rather than just one.  E.g., a Knock-Out option where the spot exchange rate must trade at or through the barrier for five consecutive days in order to be knocked out.