RNA-Seq is a lately developed technique to transcriptome profiling that makes use of deep-sequencing technology. research the usage of this method have already altered our view of the extent and complexity of eukaryotic transcriptomes. RNA-Seq additionally gives a much extra specific size of degrees of transcripts and their isoforms than different techniques. this text describes the RNA-Seq approach, the demanding situations associated with its application, and the advances made so far in characterizing numerous eukaryote transcriptomes.The transcriptome is the whole set of transcripts in a mobile, and their quantity, for a specific developmental degree or physiological condition. understanding the transcriptome is critical for decoding the functional factors of the genome and revealing the molecular components of cells and tissues, and also for know-how improvement and disorder. the key targets of transcriptomics are: to catalogue all species of transcript, which includes mRNAs, non-coding RNAs and small RNAs; to determine the transcriptional structure of genes, in phrases in their begin sites, 5′ and 3′ ends, splicing patterns and other publish-transcriptional changes; and to quantify the converting expression degrees of every transcript throughout improvement and below special situations.