Bitcoin is often described as anonymous money. It is not. Every transaction ever made is stored in a public ledger that anyone can download, search and keep forever. Addresses do not carry your name, which is why the accurate word is pseudonymous: the identity is hidden behind a label, but the label itself is permanently visible.
That distinction matters because a single link between an address and a real identity can expose everything else. Chain analysis works by clustering: when several inputs are spent together in one transaction, they are assumed to belong to the same owner. Change outputs, repeated amounts, round numbers and predictable timing all add more signal.
Identity usually enters through the edges of the network rather than the chain itself. Exchanges that perform identity checks, merchants, payment processors and even a donation address published on a personal website can connect a name to a cluster of addresses. Once that link exists, past and future payments in the same cluster can be reviewed retroactively.
Network metadata is the second leak. A wallet that broadcasts transactions through its own connection can reveal an IP address, and a block explorer visited without care can link an address to a browsing session. Privacy on Bitcoin therefore has two layers: what the ledger records, and what your network activity reveals.
Mixing addresses this first layer. By replacing the coins you deposit with unrelated coins from a reserve pool, the direct path between your old history and your new balance is broken. It does not undo information you have already published, and it does not fix careless network habits, but it removes the simple on-chain trail that automated tools follow by default.