Sitemap is must. Because Google crawler goes to site map and check all the pages to index. It is an unique place in our site where Google find all the information abut the pages and sites.
Sitemap is very necessary if you really want to index your information faster in search engines. If you don't submit your sitemap to search engines, then your articles/information not index quickly. Better if you submit your sitemap to google, bing webmaster.
Using sitemap is not necessary, but it helps crawl all pages frequently. Search engines sometimes do noy crawl a particular page, in these cases sitemap helps index and crawl efficiently.
sitemap is one of the dominating factors for google bots to crawl your site. its the little details that matter
Sitemap is a must. Especially whenever you do changes on your site, you want to keep it updated. In addition, you want to see any type of crawl errors that occur on your site and fix that as soon as possible.
Sitemap helps the crawler to get all the page links in single url and also it is required to generate xml sitemap for submit in webmaster tools which helps you alot in finding website health like crawl errors, search queries ......
Google seems to love sitemaps, although I'm not sure for how much longer, given that backlink importance is supposed to be reducing rapidly over the next few years (according to Mr Cutts). I wonder if there will be a correlation with internal linking as well. But for the meantime, definitely keep your sitemaps up to date.
It depends on your website's strength actually if your website has enough authority that Google can pick it by itself than it is not required. But for best practices people do not miss to get the maximum benefit to their website and they use it.
I always use sitemaps along with google webmaster tools. I think a lot of times my sites are indexed faster thar way however I have no proof but it seems to work for me.
I agree that having a sitemap is good and only helps your website. I use it for my robots.txt and wola!!! User-agent: * Disallow: /popup/ Sitemap: https://www.vpsaliens.com/sitemap.xml
HTML sitemaps can help users... but they can also help distribute "link juice" ("PageRank") to your important pages.