Guest posting is writing an article for someone else's website, usually in a niche the author actually knows, in exchange for a byline, a link back to the author's own site, or simply the exposure that comes with reaching a new audience. The receiving site gets free, hopefully high-quality content; the contributor gets visibility and often a backlink.
It's a legitimate practice when it's genuinely relationship- and expertise-driven, but it's also one of the more commonly abused link-building tactics: mass-produced guest posts pitched purely to harvest links, published on sites with no real editorial standard, are exactly the pattern Google's guidelines target. The difference usually comes down to intent and quality. A guest post written because the author has something genuinely useful to say to that specific audience, placed on a site with real editorial standards, benefits both sides. A guest post that exists only to plant a link, placed wherever will take it, is the version that risks a penalty rather than earning one.
