Utilize the input text as a context reference, choose the right relationship between cornerstone and marketing from the options. Options: product/material produced, manufacturer, distributed by, industry, position held, original broadcaster, owned by, founded by, distribution format, headquarters location, stock exchange, currency, parent organization, chief executive officer, director/manager, owner of, operator, member of, employer, chairperson, platform, subsidiary, legal form, publisher, developer, brand, business division, location of formation, creator.

Blogs are more than just that, they are the cornerstone of any branding or marketing campaign, every top earner has one.

Answer: industry