Do Google and Yahoo both use meta tag: http-equiv="description" or name="description" for search results?

My objective is to have the descriptive sentence of my choosing listed on the both Google and Yahoo. I was told that Google uses and Yahoo uses . I used both within the header of my website. The search results in Google reflect the descriptive sentence I inserted in the tag . In the Yahoo search results, the descriptive sentence is the first sentence of the beginning paragraph of my index page, instead of the sentence I inserted in my meta tag. I need to know which meta tag to use to accomplish my desired results, or if they both use the same tag. Thank you, in advance for your help.