A more thorough explanation:

Definition: Work product refers to material that is created in preparation for a legal case. This material is usually protected from being shared with the other side in the case, but there are some exceptions.

There are two types of work product:

• Ordinary work product: This is information that is gathered during the course of preparing for a case, such as basic facts or interviews with witnesses. If there is a good reason to share this information, such as if a witness becomes unavailable, it may be discoverable by the other side.
• Opinion work product: This is information that reflects an attorney's thoughts, ideas, or strategies related to the case. This type of work product is almost never subject to discovery.

For example, if a lawyer is preparing for a trial, they may create notes about the case, interview witnesses, or gather evidence. All of this material would be considered work product. If the other side in the case wants to see this material, the lawyer may be able to protect it from being shared, depending on whether it falls under the category of ordinary or opinion work product.