Sending Addresses counts distinct addresses that appeared on the input side of the day’s transactions. It isolates spend-side breadth, showing how many separate addresses were used to move coins out, regardless of the amount each one contributed.
A rise means the set of spenders widened. A decline means spending was concentrated in fewer addresses. The series is most useful next to Receiving Addresses or transfer volume when the question is whether spend-side activity is broad or carried by a narrower sender base.
The main caveat is that addresses are not entities. One actor can control many addresses, and broad sender counts do not imply equally broad underlying participation. Sender breadth and spent value are also different things: heavy transfer volume can come from relatively few addresses.
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