Defining a gene, a matter of interest of many disciplines, is a difficult and increasingly complicated task. Some authors think it should reflect a global concept that includes most of the structural and functional elements that compose it. In this paper, we analyze the findings that have helped to build a new concept of the gene, focusing on recent discoveries that have forced us to change the traditional definition of gene, summarized as “AND A sequence that encodes information for the synthesis of proteins or RNA”. Among these findings are alternative splicing, somatic recombination of immunoglobulin genes, regulation of gene expression at inter or intra-chromosomal levels, regulation by regulators sequences, epigenetic mechanisms or RNA; the sense and nature of transcripts, quimerism transcript, exon repetition and extragenomic inheritance. Taking into account these findings and their functional impacts we can define genes as a set of nucleic acids sequences that determine the regulation and expression of an inheritable feature.