How to make web pages with the same design


After many practice websites, I have finally made a website that is published. The problem is that if I need to change the design, i.e what is after and before (in coding) of the text that is going to be changed in every page, then I will have to change that in each of the files. Can anyone tell me about any way by which I can just change the code below and above the text. Any tag, code, software, etc that could help me, please. Thank you

You can use PHP to include header and footer.

For example, you put all the header and the menu in "header.html" and all the footer, copyright, ... in "footer.html".

The, create a index.php. In this page, you maje like that :

<?php include 'header.html'; ?>
<?php include 'footer.html'; ?>