Definition
E-commerce (electronic commerce) is the sale of products or services over the internet. In a narrow sense it means your own online shop; more broadly it includes marketplaces (Amazon, eBay, Etsy), social commerce (Instagram Shopping) and B2B platforms.
Characteristic: digital ordering, often digital payment, physical or digital fulfilment.
Models
B2C — selling to end customers (fashion, electronics, food).
B2B — selling to other businesses (wholesale, industry).
C2C — private individuals selling to each other (eBay classifieds, Vinted).
D2C (direct-to-consumer) — manufacturers sell directly, no middleman. Growing fast.
Which platform?
Shopify: quickly set up, easy to maintain, monthly cost from around €30. Ideal for most shops.
WooCommerce (WordPress): more flexible, low license cost, slightly more maintenance. Good for content-driven shops.
Custom (Next.js, Medusa): highest flexibility, higher upfront cost. Worth it at larger volumes.
Marketplace instead of shop: Amazon, eBay, Etsy as entry when you lack reach.
What it costs
Simple Shopify shop with setup and SEO basics: from €3,000.
Larger shop with custom design: €8,000–€20,000.
Fully custom: from €20,000 upwards.
Running costs: platform fees, apps, payment provider, marketing budget.