The paper presents the latest parton distribution functions (PDFs) of the proton, denoted as MMHT2014, which supersede the 'MSTW2008' sets but are derived within the same theoretical framework. The new PDFs incorporate a variety of new data, including LHC, updated Tevatron data, and HERA combined H1 and ZEUS data on total and charm structure functions. The theoretical framework has also been improved, particularly in the treatment of the $D \rightarrow \mu$ branching ratio and the inclusion of the $g \rightarrow c\bar{c}$ initiated process with a displaced vertex. The MMHT2014 PDFs are compared with the MSTW2008 sets, showing that most predictions are within one standard deviation. Key changes include an improved $u-d$ valence quark difference at small $x$ and a slight adjustment in the strange quark PDF due to LHC data and better treatment of the $D \rightarrow \mu$ branching ratio. The paper also compares the MMHT PDFs with other collaborations, such as NNPDF3.0, and discusses the impact of various data sets on the PDFs.The paper presents the latest parton distribution functions (PDFs) of the proton, denoted as MMHT2014, which supersede the 'MSTW2008' sets but are derived within the same theoretical framework. The new PDFs incorporate a variety of new data, including LHC, updated Tevatron data, and HERA combined H1 and ZEUS data on total and charm structure functions. The theoretical framework has also been improved, particularly in the treatment of the $D \rightarrow \mu$ branching ratio and the inclusion of the $g \rightarrow c\bar{c}$ initiated process with a displaced vertex. The MMHT2014 PDFs are compared with the MSTW2008 sets, showing that most predictions are within one standard deviation. Key changes include an improved $u-d$ valence quark difference at small $x$ and a slight adjustment in the strange quark PDF due to LHC data and better treatment of the $D \rightarrow \mu$ branching ratio. The paper also compares the MMHT PDFs with other collaborations, such as NNPDF3.0, and discusses the impact of various data sets on the PDFs.