Why does Google Analytics client ID cookie contain a "GA1.2." prefix?
<p>I know that an actual client ID looks like this: <code>1054613344.1468150257</code><br>
But the _ga cookies that contains the client ID has a <code>GA1.2.</code> prefix and looks like this: <code>GA1.2.1054613344.1468150257</code><br>
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<strong>What is the meaning of this prefix? Why does _ga cookie contain it?</strong></p>