Final answer:
Letters and emails are types of written communication usually meant for audiences outside the business. Memos and text messages, on the other hand, are more commonly used for internal communication within the organization.
Step-by-step explanation:
Letters are a type of written communication that is typically intended for audiences outside of the business. They are formal and often used for official correspondence with clients, partners, or other external stakeholders. For example, a business might send a letter to a potential customer to introduce their products or services.
E-mails are another type of written communication that can be used to reach audiences outside of the business. They are more commonly used in modern business communication and are often less formal than letters. An example of an external business email would be contacting a supplier to request a quote for materials.
Memos and text messages are generally used for internal communication within a business and are less likely to be directed towards audiences outside of the organization.
Learn more about Types of written communication for audiences outside of the business