Any of several types of barrier options which activates, deactivates, or explodes in response to changes in the underlying whereby the strike price is touched a certain number of times (once, twice, etc) or in case the underlying trades at or breaks through a prespecified barrier level. Once the underlying event takes place, the barrier mechanism (early exercise trigger) gets activated, and the final outcome of the option will start to be defined from that very moment.

For example, a touch knock-in option (one touch type: one touch option) allows its holder to avail early exercise when the instrike is touched once. A touch knock-out option (two touch type) allows early exercise when the outstrike is touched twice, and so on.

Other examples of touch options include in option, out option, baseball option, etc.