API
Application programming interface
An API is a set of rules that lets one piece of software ask another for data, or send it data, without a person in between.
What it means
API stands for application programming interface.1 It lets programs talk to each other directly. Each request follows a fixed format, and so does each answer.
eBay, for one, publishes APIs for product data. Its Taxonomy API tells a seller’s software which item specifics a category requires and which are optional.2 Its Inventory API takes a part’s list of compatible vehicles, linked to the part’s SKU.3
An API moves data quickly but does not check that the data is true. A wrong weight sent through one is wrong everywhere it lands.
Think of it like this
It is like ordering from a catalogue by item number. You fill in the order form exactly as the shop asks, the goods come back, and you never see the warehouse.
For example
A listing tool asks eBay’s Taxonomy API about its Diamond Rings category. The answer lists the category’s aspects, eBay’s developer name for item specifics, with the rules for each. Metal Purity is optional and chosen from a list. In eBay’s words, a ring can have “a 9k or 10k metal purity only if the ring is made of one of four types of gold”.2
Why it matters
Files suit a catalogue that changes now and then. When stock, prices or listings change daily, or across thousands of products, an API keeps systems in step without anyone exporting and importing files. It sends whatever your product data says, though, so errors travel as fast as fixes.
Not to be confused with
An API differs from a product feed. A feed is a file of the whole catalogue, sent or fetched on a schedule. An API answers each request as it is made, so a system can send or ask for just what it needs.
Sources
- MDN Web Docs. API (Glossary).
- eBay Developers Program. Finding categories for a listing.
- eBay Developers Program. Managing product compatibility.