Escherichia coli is a versatile and diverse organism that can transition from a harmless commensal to a highly pathogenic bacteria by acquiring mobile genetic elements. It can cause a wide range of diseases, including gastroenteritis and extraintestinal infections. Eight E. coli pathovars have been well characterized, each using a variety of virulence factors to subvert host functions and cause disease. Recent advances in understanding the molecular mechanisms of these pathovars are highlighted in this review. The pathogenic mechanisms of E. coli involve adhesion to host cells, often through fimbriae or pili, followed by subversion of host cell processes, including signaling pathways, to facilitate invasion, immune evasion, and colonization. Different pathovars, such as enteropathogenic E. coli (EPEC), enterohaemorrhagic E. coli (EHEC), and uropathogenic E. coli (UPEC), use distinct strategies to cause disease. For example, EPEC uses the locus of enterocyte effacement (LEE) to form pedestals beneath host cells, while EHEC uses Shiga toxin to cause severe disease. UPEC, which causes urinary tract infections, uses type 1 pili to adhere to the uroepithelium and evade immune responses. The evolution of pathogenic E. coli is influenced by the acquisition and loss of mobile genetic elements, including pathogenicity islands (PAIs) and plasmids. These elements contribute to the genetic diversity and adaptability of E. coli pathovars. The genomes of pathogenic E. coli are larger than those of commensal isolates, with a core genome of approximately 2,200 genes and a pan-genome of around 13,000 genes. This genetic diversity allows for the emergence of various pathovars with distinct virulence mechanisms. The review also discusses the pathogenesis of various E. coli pathovars, including their interactions with host cells, the role of virulence factors, and the mechanisms by which they cause disease. For example, EHEC causes haemolytic uraemic syndrome, while EIEC causes bacillary dysentery. The review highlights the importance of understanding these molecular mechanisms to develop effective treatments and prevent infections caused by E. coli.Escherichia coli is a versatile and diverse organism that can transition from a harmless commensal to a highly pathogenic bacteria by acquiring mobile genetic elements. It can cause a wide range of diseases, including gastroenteritis and extraintestinal infections. Eight E. coli pathovars have been well characterized, each using a variety of virulence factors to subvert host functions and cause disease. Recent advances in understanding the molecular mechanisms of these pathovars are highlighted in this review. The pathogenic mechanisms of E. coli involve adhesion to host cells, often through fimbriae or pili, followed by subversion of host cell processes, including signaling pathways, to facilitate invasion, immune evasion, and colonization. Different pathovars, such as enteropathogenic E. coli (EPEC), enterohaemorrhagic E. coli (EHEC), and uropathogenic E. coli (UPEC), use distinct strategies to cause disease. For example, EPEC uses the locus of enterocyte effacement (LEE) to form pedestals beneath host cells, while EHEC uses Shiga toxin to cause severe disease. UPEC, which causes urinary tract infections, uses type 1 pili to adhere to the uroepithelium and evade immune responses. The evolution of pathogenic E. coli is influenced by the acquisition and loss of mobile genetic elements, including pathogenicity islands (PAIs) and plasmids. These elements contribute to the genetic diversity and adaptability of E. coli pathovars. The genomes of pathogenic E. coli are larger than those of commensal isolates, with a core genome of approximately 2,200 genes and a pan-genome of around 13,000 genes. This genetic diversity allows for the emergence of various pathovars with distinct virulence mechanisms. The review also discusses the pathogenesis of various E. coli pathovars, including their interactions with host cells, the role of virulence factors, and the mechanisms by which they cause disease. For example, EHEC causes haemolytic uraemic syndrome, while EIEC causes bacillary dysentery. The review highlights the importance of understanding these molecular mechanisms to develop effective treatments and prevent infections caused by E. coli.