For questions about Orlicz spaces, which are a generalization of classical Lebesgue spaces $\mathbb L^p$.
Orlicz spaces are Banach spaces that are generalisations of the classical Lebesgue space $L^p$.
The $L\log^+ L$ class (allowing the Hilbert transform to be integrable on $L^1$) is an example of an Orlicz space.
The Sobolev space $W^{1,p}_0$ is embedded in the Orlicz space for a subset of $\mathbb{R}^n$ with Lipschitz boundary.