The Google Keyword Planner tool is a keyword research tool that helps you find keywords to build optimal search engine campaigns. Using the tool, you can discover keywords that you can optimise your site for to achieve higher search engine rankings.
When you first log in, you'll be presented with this screen giving you 3 options to find keywords:
Here you can find keywords by:
Searching via phrase, keyword or website
Getting search volume data and trends
Multiplying keyword lists to get new keywords
Once inside, you'll be able to filter the keywords by a number of options.
The filtering options in Keyword Planner including via:
While the temptation is to choose keywords that have the highest search volume, bear in mind, these keywords are often the most competitive. As a result, it can take months or years (if ever) for you to rank highly for these terms.
Note: You will need a Google account in order to start using the service.
While there are paid tools that can make uncovering low competition faster, such as Long Tail Pro, Google Keyword Planner is generally the best place to start when looking for keywords that will go on to form the basis of your site's search engine optimisation.