How does first source differ from first-click attribution?

First source is a descriptive property on the user and says nothing about conversions; it only records where the person entered. First-click attribution is a credit-splitting rule that makes that same point the owner of the whole conversion, and only if it falls inside the lookback window.

First Source

Intermediate

Updated Jul 11, 2026 Shahin editorial 2 min read

PronunciationEN/fɜːrst sɔːrs/

First source is the origin recorded for a user's very first visit and kept unchanged on later visits, so the point of discovery stays visible.

The value is a durable property on the user and behaves as the opposite of the per-session source, which is recomputed on every visit. Its validity depends entirely on identifier persistence: a cleared cookie, a private window or a second device manufactures a false first visit, which inflates whichever channel people return through, usually branded search or direct. The second point is that first source answers how someone discovered the product, not what produced the purchase, and on long buying cycles the two are often unrelated.

FAQ