The HTML "tr" element specifies that the markup contained inside the "tr" block comprises one row of a table, inside which the "th" and "td" elements create header and data cells, respectively, within the row. The "td" element creates a single data cell or column. "tr" and "td" are used to create my calculator. In the "table", I first used the "tr" to create my rows. Then, I put "td" and placed inside the "tr" to make my columns. The "tr" supports the "td" to stay inside the row. The "td" then puts the buttons into columns inside a row. Without the "td", the buttons would have been too close or too far apart from each other. These two tags work together to make the buttons stay in place and look perfectly fine.