The meta description is the short piece of text under your title in the Google results. It does not determine your ranking, but it does determine whether people click — think of it as your free ad.

What to watch for

• Keep it around 150 characters, otherwise Google cuts it off.
• Start with the most important point and mention a concrete benefit.
• End with an invitation ('Read more', 'Browse the range').
• Write a unique description for every page.
• Work your main keyword in naturally.

Compelling titles go hand in hand with this — see Compelling SEO titles. How to set this per page is covered under SEO.