SEO, short for search engine optimization, refers to a collection of methods and practices that are employed to enhance the visibility and ranking of a webpage or website on search engine results pages (SERPs). The ultimate goal of SEO is to boost the quantity and quality of organic traffic that a website receives. The SEO techniques that are commonly used include optimizing website content, meta tags, image alt tags, backlinks, and other elements that search engines utilize to assess the relevance and authority of a webpage.

In contrast, digital marketing encompasses a wider array of activities that are designed to promote a product or brand through digital channels. While SEO is a part of digital marketing, digital marketing also includes other channels, such as social media, email marketing, PPC advertising, and content marketing. The purpose of digital marketing is to increase brand recognition, generate leads, and drive sales through various digital channels.

The three main types of SEO are on-page SEO, off-page SEO, and technical SEO. On-page SEO focuses on optimizing website content, off-page SEO centers on building backlinks, and technical SEO deals with website structure and code optimization.

To sum it up, SEO is a subset of digital marketing that focuses specifically on improving the visibility and ranking of a website on search engine results pages, whereas digital marketing is a broader term that includes all marketing activities that are carried out via digital channels.