A meta description is a short summary you can give a web page. The old article argued that this text matters to a searcher’s decision even without directly determining rankings. The idea remains useful, but its appearance is less predictable than the article suggested.
Write for the question behind the search
Google explains that it usually generates a search snippet from the page itself. Sometimes it uses the meta description when that fits better. The same page may therefore show a different snippet for different searches. You can offer a description, not force its use.
In one or two sentences, say what a visitor will find. A product page may name the item, its use and a distinguishing feature. An article can mention the question it answers. Avoid a row of keywords or a promise the page does not fulfil. Keep the visible opening of the page clear too, because it may become the snippet.
Make it specific to each page
A generic description repeated everywhere helps little. Start with important pages and write a distinct summary for each. On a large site, a careful template may help if it includes genuinely different page details. Read the result as a stranger: would you understand why to click?
Do not measure clicks alone. See whether visitors find what the description promised after arriving. An enticing sentence that creates the wrong expectation helps nobody. A meta description is a chance to explain the content, not a trick for controlling search results.