Some websites will have one or possibly more than one sidebar, but some websites do not have any sidebars at all.
A sidebar is found on either the left or right side of a website, or both. Sometimes you’ll see two sidebars right next to each other on the left or right side of the website.
On mobile phones and some tablets and devices, the sidebar might shift to being below the main content of the page you are on.
The sidebar of a site could have any number and variety of elements.