In options, much like stocks, there are two main positions, long and short. For better communication between brokers and traders and due to the nature and strategies of options, someone has to specify thoroughly what transaction he/she wants to perform. So we can divide options transactions in four categories:

1. Buy to open

Buy a call or put to open a position (opening of a long position in an option).

2. Buy to close

Buy a call or a put to close an already existing short position in an option.

3. Sell to open

Sell a call or put to open a position (short selling or writing of an option).

4. Sell to close

Sell a call or put to close an already existing long position in an option.