Keyword Tool is free online keyword research instrument that uses Google Autocomplete to generate hundreds of relevant long-tail keywords.
Google Autocomplete is a feature used in Google Search. Its purpose is to speed up the searches performed by users on Google.
The search terms that are suggested by Google Autocomplete are based on a number of different factors, one of them is how often users were searching for a particular term in the past.
Keyword Tool helps you use Google Autocomplete for keyword research. It extracts Google suggestions and presents it to you in a convenient form.
To generate long-tail keyword suggestions, Keyword Tool prepends and appends the term, that you specify with different letters and numbers. It also allows you to choose a specific Google domain (192 Google domains supported) and language (83 languages available) combination.
Keyword Tool generates over 750 keywords in the language of your choice. You can export the keywords and use them for content creation, search engine optimisation, PPC or other marketing activities.
— Rand Fishkin (@randfish) June 23, 2014
Note: Also see the Yahoo! Group on which I present similar issues:IMRo. To join, email firstname.lastname@example.org and reply to the confirmation email.