A landing page is where a visitor ends up after clicking a link from an email, an ad, or another campaign. If that campaign is drawing people in with a specific offer, the page needs to hold up its end of the deal with content the visitor can actually connect to what brought them there. Send visitors to a generic homepage or something unrelated instead, and many will leave because they can't find what they came for.
Message match is the term for that connection: the headline, imagery, and offer on the landing page should echo whatever the ad or email promised closely enough that a visitor immediately recognizes they've arrived in the right place. A campaign promoting "20% off running shoes" that lands on a general shoe category page, rather than a page actually featuring the discount, breaks that match and tends to show up as a weak conversion rate even when the ad itself performed well. Because a landing page usually exists to drive one specific action, sign up, buy, request a demo, it's typically built leaner than a normal page too: fewer distractions, fewer competing links, and a single, clear next step rather than the full site navigation pulling attention elsewhere.
