I am beginner in html / website design. I have 4-5 webpages. All these pages have top banner, left sidebar & right sidebar. At present I am writing html code in all the 4-5 pages for these above elements. Is there a way, I just write the code once (in one file) and this file can be called / included in all the 4-5 pages. In case, I have to make change I just need to update one file and the change gets reflected in all the pages.