Correspondence

I came across a job description notice below.
I then come up with one question what does the word "correspondence" as in the line "prepare documents and correspondence ..." mean?

Correspondence Clerks

• Prepare documents and correspondence such as damage claims, credit and billing inquiries, invoices, and service complaints.
• Compile data from records to prepare periodic reports.
• Present clear and concise explanations of governing rules and regulations.
• Read incoming correspondence to ascertain nature of writers' concerns and to determine disposition of correspondence.