How can I add a part to my website that will be placed on all pages and after a while update it on all pages?

Question

I want to add a section to my site that will be placed on all pages and updated every day

Answer 1

You can do that with a templating language like "Jinja2" for Django projects.
You can have one html file for the header and "include" it in every other files(extends x.html)

Answer 2

I want to put a section above my web site to place an ad or post inside it on all pages.
And I can change it every day without having to change on all pages

Answer 3

like a counter or like a clock?
can you explain a little more about what you want to do?
with vue.js or react.js is ease just like a component.
if just HTML CSS and js.
you can create a div and copy all the logic for the js and styles to every page that you want that component to be placed at

Answer 4

or pug are some templating but you have to have a back end to be able to do that