The Ontario Council of University Libraries has an excellent toolkit on communication accessibility. They state:
Accessible communication benefits all audiences by making information clear, direct and easy to understand. It takes into consideration the various barriers to accessing information, and provides opportunities for feedback.
Libraries communicate with users in a variety of ways, including in person, through printed materials, and via online spaces such as websites and social media. Providing clear and concise information, targeted to a particular audience, is important to ensure that all users have equal access to information. Although the vehicle for this information may change, the message is the same.
Libraries should aim to have all communications be accessible, including: