What are two common formats for a business letter?

The two most common business letter formats are:

block format; all of the lines of the letter are justified to the left margin.

modified block format; the lines of the letter are justified to the left margin with the exception of:

-the return address and date at the top,

-the complimentary closing name, and signature of the sender at the bottom,

which are tabbed to the center of the page or justified to the right margin.