Following the discussion of the various approaches
to PDF fitting in the previous section,
next we  compare the results a number of 
state-of-the-art PDF analysis.
%
This comparison is organized in terms of specific
PDF flavour combinations relevant for phenomenology.
%
We begin by discussing the gluon PDF,
next we turn to the quark flavor
separation, 
and subsequently we study the strange and charm content
of the proton.
%
In the following, we compare  the ABMP16, CT14, MMHT14,
     and NNPDF3.1 NNLO sets, all with $\alpha_{S}(m_Z)=0.118$.
     %
     We will present results both at low ($Q=1.7$ GeV)
     and high ($Q=100$ GeV) scales, though
     for the former case ABMP16 
     cannot be included since their set
     with $\alpha_{S}(m_Z)=0.118$ is only available in the $n_f=5$ scheme,
     and therefore can only be used for $Q > m_b$.
     %
     Here we will
     only show a representative selection of PDF comparisons:
other results, including with PDF sets not shown
here, can be straightforwardly produced using the {\tt APFEL-WEB}
online PDF plotting interface~\cite{Carrazza:2014gfa}.

\subsection{The gluon PDF}\label{sec:structure.gluon}
\input{6-structure/subsec-gluon.tex}

\subsection{Quark flavor separation}\label{sec:structure.flavoursep}
\input{6-structure/subsec-quarkseparation}

\subsection{Strangeness}\label{sec:structure.strange}
\input{6-structure/subsec-strangeness}

\subsection{The charm content of the proton}\label{sec:structure.charm}
\input{6-structure/subsec-charm}



