A few others have written excellent content on the subject. Michael Haupt's article here is an already deep dissection of the practice.
Early stage startups, possibly like your own, are at a unique stage of business development where agility and ingenuity are a must to be able to find out what works and what doesn't, all while making it to the next round of funding. Marketing specialists, most often hired by large, well-funded businesses, tend to have a laser-focus on one or two areas of the marketing stack. These specialists also generally are not "big picture" focused, taking into account all the working parts that it takes to run a fledgling business - everything from lead generation and fund raising, to what's going on with the development team. This class of marketer might specialize in CPC, email marketing, UX, or SEO, which is perfect for a big business that already knows what it needs and has established roles. But for an early-stage startup that is still experimenting and pivoting, full stack marketing will get them further.
A full stack marketer is a generalist, able to operate at every level of the stack, and if they don't have a certain skill, they do the research to learn that skill. They are marketers with an entrepreneurial spirit and a desire to constantly learn new things and push beyond what is comfortable and known to them. They are leaders, and effective project managers, with a grasp for the full context each marketing practice has in relationship to the business goals as a whole, always keeping in mind ROI, revenue, and KPI's.
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