Memo and destination tag fields: when you must use one
Some deposits need a memo or tag as well as an address, and leaving it out can lose the funds. Which networks use them and why.
Some networks and some services ask for a second field alongside the address — a memo, a destination tag, or a note. It is not optional decoration. On the chains that use it, it is how your deposit is identified.
Why it exists
When a service pools many customers' funds into one address, the address alone cannot say whose deposit arrived. The memo or tag carries that information.
On networks designed around this pattern — XRP, XLM, ATOM, EOS among others — the field is part of normal operation rather than an edge case.
What happens if you omit it
The transfer succeeds on the blockchain. The funds reach the shared address and simply cannot be attributed to you.
Recovery depends entirely on whether the receiving service has a manual process for it. Some do, slowly, with proof. Some do not, and the funds are effectively lost despite nothing having technically gone wrong.
The rule
If a deposit page shows a memo or tag field, fill it in exactly as given, every time, even for a repeat deposit. The value can differ between deposits.
If no such field is shown, do not invent one.
The networks BYCRYPTO supports — Tron, Ethereum and Bitcoin — do not use memos or tags, and every account is given its own address rather than sharing one. So there is no extra field to remember here. It is worth knowing because you will meet it elsewhere.