Short definition
Content marketing is the strategy of attracting and retaining customers by publishing useful content (articles, videos, podcasts, guides) instead of paying for attention.
In depth
Content marketing compounds. Each well-built page can rank, earn citations, get linked, and produce leads for years. The best content marketing is also the best GEO and SEO — direct, sourced, structured, and built around the questions a target buyer asks. For service businesses the highest-leverage formats are case studies, comparison pages, glossary terms, and definitive buying guides.
Example
A roofing firm publishes one cornerstone article a month for 18 months. By year two, organic content is producing 60% of new leads at one-third the CPL of paid.