An option holder is an investor who owns an options contract. This person has the right, but not the obligation, to buy or sell an underlying asset at a specific price (known as the strike price) on or before a certain date (the expiration date). 

There are two types of option holders: call option holders and put option holders. 

A call option holder has the right to buy the underlying asset, while a put option holder has the right to sell the underlying asset. 

Important to note, holding an option does not equate to ownership of the actual asset; it merely confers the right to buy or sell that asset. 

The main motivation for an investor to be an option holder is to profit from expected price changes of the underlying asset without having to invest as much capital upfront as they would need to buy or sell the actual asset outright.