This is how to check back links with a simple special search for your site on Google Search.
The following is an example of a special search for back links to my website with Google Search. It lists links from other websites to my website and excludes my own website from the results.
"www.micski.dk" -site:www.micski.dk
The results can be checked and explain spikes in number of visitors, let you solve dead links and other kinds of interesting stuff.