A meta description is the short blurb of text that appears under your page's title in Google's search results. It doesn't directly change your ranking, but a good one convinces people to click your result instead of a competitor's.
Also known as: Meta desc, SERP description, snippet description
In plain English
The meta description is the ~150-character summary Google shows beneath your page title in search results. It's your ad copy for free - the pitch that convinces someone to click your result over the nine others.
Why it matters for your business
It doesn't directly affect rankings, but it strongly affects click-through rate - and a great position with a weak description loses clicks to a worse-ranked competitor with a compelling one. Every important page should have a unique, written description.
When you'll run into it
For every indexable page. Write it for humans (benefit + call to action), include the primary keyword naturally, and keep it under ~160 characters.
A real example
Example: for a page about emergency WordPress fixes, a meta description like "WordPress site down? We diagnose and fix critical errors, white screens, and hacked sites at a flat rate - most repairs done the same day." appears under your blue link in Google results and is often the difference between a click and a skip.
Run into this on your site?
Speed Optimization