Paid Ads = OK
Paid links that look organic = bad.
You are not allowed to pay to increase your ranking. You can buy ads on Google or another site and that's ok as long as they are marked as ads.
You are not allowed to pay to increase your ranking. You can buy ads on Google or another site and that's ok as long as they are marked as ads.
Does every advertisement necessarily carry a 'Advert' banner?
If you're asking how does Google know if a link was paid? It has some algorithmic ways, and it also relies on paid link reports from competing webmasters.