MG-RAST  MG-RAST is an open-source web application server that suggests automatic phylogenetic and functional analysis of metagenomes. It is also one of the biggest repositories for metagenomic data. The name is an abbreviation of "Metagenomic Rapid Annotations using Subsystems Technology". The pipeline automatically produces functional assignments to the sequences that belong to the metagenome by performing sequence comparisons to databases in both nucleotide and amino-acid levels. The applications supplies phylogenetic and functional assignments of the metagenome being analysed, as well as tools for comparing different metagenomes. It also provides a RESTful API for programmatic access. The server was created and maintained by Argonne National Laboratory from the University of Chicago. In December 29 of 2016, the system had analyzed 60 terabase-pairs of data from more than 150,000 data sets. Among the analyzed data sets, more than 23,000 are available to the public. Currently, the computational resources are provided by the DOE Magellan cloud at Argonne National Laboratory, Amazon EC2 Web services, and a number of traditional clusters. MG-RAST has been developed as an effort to have a free, public resource for the analysis and the storage of metagenome sequence data. The service removes one of the primary bottlenecks in metagenome analysis: the availability of high-performance computing for annotating data. Metagenomic and metatranscriptomic studies involve the processing of large datasets and therefore they can require computationally expensive analysis. Nowadays, scientists are able to generate such volumes of data because, in the recent years, the sequencing costs have reduced dramatically. This fact has shifted the limiting factor to the computing costs:for instance, a recent study of the University of Maryland, estimated a cost of more than $5 million per terabase using their CLOVR metagenome analysis pipeline. As the size and number of sequence datasets continue to increase, costs related to their analysis will continue to rise. Additionally, MG-RAST also works as a repository tool for metagenomic data. Metadata collection and interpretation is vital for genomic and metagenomic studies, and challenges in this regard include the exchange, curation, and distribution of this information. The MG-RAST system has been an early adopter of the minimal checklist standards and the expanded biome-specific environmental packages devised by the Genomics Standards Consortium, and provides an easy-to-use uploader for metadata capture at the time of data submission. The MG-RAST application offers automated quality control, annotation, comparative analysis and archiving service of metagenomic and amplicon sequences using a combination of several bioinformatics tools.