New vs Returning Users

New vs returning is the split of the users in a reporting period into those seen for the first time and those who had already visited before.

The split is read as an audience mix: a rising new share suggests acquisition is working, a rising returning share suggests loyalty. Both halves come from the same first-seen timestamp on a browser identifier, so anything that resets identifiers moves users out of the returning bucket and into the new one and tilts the picture. The comparison is only meaningful between ranges of equal length, because the labels are defined against the range boundaries. The mistake to avoid is reading a growing new share as growth while total users stay flat, which usually means the loyal base is shrinking.