What the meta title and description do
These are two fields in the head of a page. The title element supplies the clickable blue line in a search result and the label on a browser tab. The meta description supplies the grey summary underneath it. Neither appears on the page itself, so a visitor never reads them once they have arrived — their whole job is done in the result listing.
Their weight is different. The title tag is a genuine ranking input: it is one of the clearest statements a page makes about its subject. The meta description is not used for ranking at all. It earns its place by influencing whether someone clicks, which is a slower and less direct route to the same outcome.
Neither is guaranteed to be shown. Search engines rewrite titles when they judge yours a poor match for the query, and they very often replace descriptions with a sentence lifted from the page. Treat what you write as a strong preference rather than an instruction.
Why the meta title and description matter
Ranking gets you into the list; the snippet decides who chooses you from it. Two pages sitting next to each other can attract very different numbers of clicks depending on whether their titles name what the reader wants. That makes the snippet the cheapest improvement available on a page that already ranks.
They also set the expectation the page has to meet. A title that promises pricing and a page that hides it produces a visitor who leaves immediately, which helps nobody. Written honestly, the pair works as a filter: the people who click are the people the page was written for.
Where meta titles and descriptions go wrong
Duplication is the most common defect on a real site. Templated titles across a product catalogue, or a description copied to every location page, leave search engines nothing to distinguish the pages by and readers no reason to prefer one.
Keyword stuffing is the next. A title built from repeated phrases separated by pipes reads as spam to a person and is one of the things that prompts a rewrite. Fitting the brand name into every title also eats the space where the useful words should be.
The third is length. Titles and descriptions are cut off by pixel width rather than a fixed character count, so an over-long title loses exactly the ending you cared about. The other extreme is just as wasteful: an empty description invites the engine to assemble one for you, and a blank field on an important page is a missed opportunity rather than a neutral choice.
Getting it right
Write the title around the single thing the page is for, with the most distinctive words at the front where truncation cannot reach them. Write the description as a plain sentence that says what the reader will find and what makes it worth opening — not a summary of the page, but a reason to choose it.
Make every one on the site unique, check the length before publishing with a tool such as the meta title and description checker, and revisit them for pages that rank well but attract few clicks. That combination — good position, poor click rate — is usually a snippet problem rather than a content problem, and it is one of the quickest fixes in search.