According to Wikipedia ,
A site map (or sitemap) is a list of pages of a web site accessible to crawlers or users. It can be either a document in any form used as a planning tool for Web design, or a Web page that lists the pages on a Web site, typically organized in hierarchical fashion.
Above statement sound a bit technical to you? No worry, lets us simplify it in layman terms.
Do you know what is navigation menu? No? see this (highlighted in red):
A lists of the navigation menu is called sitemap. ( Actually there are more info about sitemap. But, it is enough to get understand for non-IT person)
How is my sitemap looks like for above design?
Sitemap 1
Sitemap 2
Note : every page in Sitemap 2 also have its respective navigation menu.
So, when someone ask “Could you give us your website sitemaps?”, now you know what are the information to give them.
Hopefully above helps!
P/S : If you are techincal person and wish to know more details about sitemap. You always can refer to wikipedia.
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