What is the meaning of "service bits" in Bitcoin?

What is the meaning of "service bits" in Bitcoin?

// Note that of those which support the service bits prefix, most only support a subset of
// possible options.
// This is fine at runtime as we'll fall back to using them as a oneshot if they don't support the
// service bits we want, but we should get them updated to support all service bits wanted by any
// release ASAP to avoid it where possible.

Reference: https://github.com/bitcoin/bitcoin/blob/master/src/chainparams.cpp#L116

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