The writer, also known as the seller, is the party that sells the option contract to the buyer (holder). The writer is obligated to buy or sell the underlying asset at the strike price if the holder exercises the option.

As the writer, they have the following obligations:

- Call option writer: The obligation to sell the underlying asset at the strike price.

- Put option writer: The obligation to buy the underlying asset at the strike price.

The writer receives the premium from the holder and is exposed to potential losses if the option is exercised. The writer's goal is to collect the premium and have the option expire worthless, allowing them to keep the premium as profit.

It's important to note that the writer is also referred to as the option seller or the short position.