I have a question about meta description tags. I've always used them when optimising my site and always thought they were important for Google to realise how relevant your site is to a given keyword. This would usually be the snippet that shows up in the SERPs
However recently, I've noticed that the snippet in the SERPs is different depending on the keyword that you use. It is showing the same page and same URL, but sometimes the snippet is taken from the meta description, and sometimes it is taken directly from text on the page.
My question is - do Google use the meta description tag to determine where you rank, or do they just pick a snippet that they feel would be more relevant to the user?
Thanks for any help,