Klaviyo is an email marketing platform.

Email marketing is directly marketing a commercial message to a group of people using electronic mail email. wikipedia.org

"Marketing automation refers to software platforms and technologies designed for marketing departments and organizations to more effectively market on multiple channels online (such as email, social media, websites, etc.) and automate repetitive tasks. Marketing departments, consultants and part-time marketing employees benefit by specifying criteria and outcomes for tasks and processes which are then interpreted, stored and executed by software." wikipedia.org

The planning, executing, tracking and analysis of direct marketing campaign. wikipedia.org

Mailchimp helps you design email newsletters, share them on social networks, integrate with services you already use, and track your results. It's like your own personal publishing platform. wikipedia.org

PSD to Mailchimp template conversion is the process of converting an Adobe Photoshop file (.psd) into an HTML email template for use with the email marketing service MailChimp.

HyperText Markup Language (HTML) is the main markup language for web pages. HTML elements are the basic building-blocks of webpages. wikipedia.org

Email marketing is directly marketing a commercial message to a group of people using electronic mail email. In its broadest sense, every email sent to a potential or current customer could be considered email marketing. It usually involves using email to send ads, request business, or solicit wikipedia.org