Note! Google often shows search results for general meanings, rather than specific words and phrases. When you search for a phrase in Google, you’ll see the keyword bolded in the search results. Look closely and you may find words you didn’t search for bolded in those same search results. For example, a search for “HVAC repair” returns search listings with phrases such as “heating” and “air conditioning.”
It’s important to note that entire websites don’t rank for keywords — pages do. With big brands, we often see the homepage ranking for many keywords, but for most websites this isn’t usually the case. Many websites receive more organic traffic to pages other than the homepage, which is why it’s so important to diversify your website’s pages by optimizing each for uniquely valuable keywords.
3) Google: This is pretty straight forward but it’s the main reason I like it. I search for my main seed keyword in Google, and use the keywords that Google itself highlights in bold on the search results, plus the “Searches related to” section at the bottom to get keyword variations or LSI. That’s basically what Google is telling you that topic is about. No need for a thousands other tools. I use these to optimize the on page of my target pages as well.
Of all the tools listed in this article, Moz Link explorer is an old one & quite popular.  If you want to compare backlinks between two or more domains, Open Site Explorer is worth trying. This tool works best when you have a paid account of SEOMOZ though a free version of this tool is good enough to get you started checking the backlinks of your site and the sites of your competitors.