我如何使用常见的大量经常被重用的HTML源代码?

A slew of pages I've written for one of my web projects share some 144 identical lines of code, reproduced in each file. If I update one of those lines, I have to go back through ALL of the pages that share the code and update for each page. Is there a straightforward way to include HTML from a separate file?A slew of pages I've written for one of my web