Usually, the various search engines provide their own keyword suggestion tools, which also include the number of searches for each of those keywords. The keyword researcher uses this information to select the correct keyword, depending on the SEO goals of the website. Around 20–25% of searches are very specific long tail keywords entered into Google every single day. It's easy to rank said keywords when there is the right amount of content and backlinks to match. Keyword research is a valuable and high return activity in the search marketing field.
2) SEMrush- This tool offers fantastic competitive research around domains to find what keywords could be driving traffic for your competitors. Looking at paid keywords ad spend can also help you know which keywords might have monetary value worth pursuing organically. If a competitor is willing to spend a high ad budget on terms and you think they do a good job running their ad campaign, then its a good indication it is worth organic ranking effort.
Long Tail Pro is a keyword research tool that helps you quickly find low competition keywords for your website. In particular, the tool is built for people doing SEO (search engine optimization) as opposed to people doing paid ads (Google Adwords PPC). I'm sure there are some advertisers that use the tool for paid ad keyword research, but the tool was built for SEO keyword research.