A blog is essential for a business website because it boosts SEO by providing fresh, keyword-rich content, which attracts organic traffic. It establishes authority and credibility by showcasing expertise and offering valuable insights, while also engaging and educating the audience. Blogs drive leads and conversions through strategic calls to action and support social media marketing by providing shareable content. Additionally, they deliver long-term results, improve customer retention, and allow businesses to share their brand story, fostering deeper connections with customers.