The first step to using cryptos is to create a wallet. The wallet principle is based on a pair of two keys – public and private. The private key entitles the user to crete transactions – the private key must remain secret, otherwise anyone with the private key can handle your cryptocurrency. Loss of private key leads to irreversible loss of cryptocurrency.
A public key is a publicly known address to which another user can send money (cryptocurrency) on a given network, just like the bank account number.
Each blockchain transaction has its transaction number – the so-called transaction ID, otherwise also called Txid. The vast majority of wallets show the TXID after user sends the funds. The transaction can also be found in the block explorer of the given currency.
Search for your public key in the block explorer and you will find all the transaction IDs for all your trasactions.
TXID is unique token, for example: 1c12443203a48f42cdf7b1acee5b4b1c1fedc144cb909a3bf5edbffafb0cd204
Each cryptocurrency is built on its own blockchain, which records user transactions. Blockchains are incompatible with each other. Sending BTC to a public address in the Litecoin blockchain will result in irreversible loss of bitcoins.
Exceptions are platforms such as Ethereum or EOS. These serve for the simplified creation of tokens on a given network. However, native tokens can only be sent to addresses on a given network – Ethereum supports multiple tokens, but can only be sent on Etehereum blockchain. Still, you can not send BTC to Ethereum addres – and any attempt will result in irreversible loss of funds.