Entering your URL

In a URL, the ? (question mark) marks the start of the query string — the part of the URL that sends parameters or options to the web server.

🧩 Example

In your example:

https://ourworldindata.org/grapher/pupil-teacher-ratio-for-primary-education-by-country.csv?v=1&csvType=full&useColumnShortNames=true

  • The part before the ?

    https://ourworldindata.org/grapher/pupil-teacher-ratio-for-primary-education-by-country.csv

    → is the base URL — it tells the browser what resource to access.

  • The part after the ?

    v=1&csvType=full&useColumnShortNames=true

    → is the query string — it contains parameters that modify or specify how that resource should be delivered.

⚙️ How query parameters work

  • Each parameter is a key–value pair, separated by =.

    • Example: v=1

  • If there are multiple parameters, they’re joined by &.

    • Example: csvType=full&useColumnShortNames=true

So:

?v=1&csvType=full&useColumnShortNames=true

means:

  1. v = 1
  2. csvType = full
  3. useColumnShortNames = true

💡 Why it’s used

Websites and APIs use query parameters to:

  • Request specific versions of data (e.g., v=1)
  • Choose a format (e.g., csvType=full)
  • Filter or sort results (e.g., ?country=India&year=2020)
  • Control display options (e.g., useColumnShortNames=true)

🧠 Analogy

Think of the URL like a street address, and the query string like special instructions for the delivery:

“Deliver to 123 Main St (that’s the base URL), but bring the large box and ring the back doorbell (those are the query parameters).”