SEMrush tracks 95 million keywords and 40+ million domains to gain insights into digital marketing strategies. The document recommends identifying real competitors through tools like SimilarSites.com and analyzing competitors' paid keyword strategies using SEMrush, KeywordEye.co.uk, and KeywordToolDominator.com to build an effective keyword list. It emphasizes using exact match keywords and considering transactional versus informational intent to minimize wasted spending through trial and error.