I assume you mean in domains,since dashes are not normally used in keywords for optimizing a site.
There is a big differentce between "foreignexchangetrading" vs "foreign-exchange-trading".
In the first example, most search engines will match a search for "foreign exchange trading" foreignexchangetrading.xxx, but they will not match one for "exchange trading" because the search engine will not be able so determine where the other words are in the domain.
But if you use dashes, the search engines treat those like spaces and so you can match to a word or words that are in the domain.
|