HTTP header is a key-value pair sent in an HTTP request or response that provides additional information about the request or response. It's like the metadata of your API calls - not as exciting as the actual data, but apparently it's still important.

How to use it in a sentence

• I was trying to debug this API integration, and after hours of banging my head against the wall, I finally realized I was sending the wrong HTTP header. Rookie mistake, I know.

• My tech lead keeps going on about how we need to add caching HTTP headers to improve performance. I'm like, "Sure, I'll get right on that, right after I finish this other thing that actually matters."

If you actually want to learn more...

• Enterprise Integration Using REST covers versioning strategies using HTTP headers vs URLs. Apparently coordinating cross-service upgrades is "tricky" - who would've thought?

• Data Fetching Patterns in Single-Page Applications mentions how modern web apps send hundreds of requests per page, many using custom HTTP headers. All so pages load 0.2 seconds faster - totally worth the added complexity.

• Detecting Interaction Effects in Online Experimentation talks about how ad tracking and experimentation systems use HTTP headers to customize content. As if ads weren't annoying enough already.

Note: the Developer Dictionary is in Beta. Please direct feedback to skye@statsig.com.