It's essential to distinguish between two distinct types of software when using Bitcoin: the node and the wallet.

A Bitcoin node, as mentioned above, is a piece of software that actively participates in the peer-to-peer network. It performs three main tasks:

A Bitcoin wallet, on the other hand, is a piece of software designed to store and manage your private keys. These keys enable you to spend your bitcoins by satisfying the locking scripts (typically through a signature). A wallet can connect to a node (whether local or remote) in order to consult the status of the blockchain and broadcast the transactions it builds, but it is not, as such, a participant in the network.

In some cases, these two functions coexist within the same software, as is the case with Bitcoin Core, which serves as both a full node and a wallet. However, many popular wallet programs (Sparrow, Bluewallet, etc.) require a connection to an external node (whether your own or a third party's) to broadcast transactions and determine the wallet balance.