Many keyword researchers and copywriters automatically assume that searchers type in a natural word order all of the time. If a potential customer is researching prices for help desk software, that person might type in the keyword phrase “help desk software prices” (without the quotation marks) directly into a commercial search engine’s search box. This is an specific search and is about someone really searching a help desk software to buy.
When the search has just one or two words, the user is researching. This is a kind of generic search and brings a lot of results on search engines. You can try the query above and another search using only “help desk”. The first will show 10 results of about 7,850,000 pages and the second of about 98,500,000 pages.
If you are targeting a product or service to sell you’ll need to user keyword phrase 3 to 5 words. Google has a beta version that can help you find a niche and see search trends.