Helix is a set of overall design principles and conventions for Sitecore development. With the evolution of Sitecore itself and large enterprise solutions growing as per company’s business, there is a requirement to define a standard which simplifies the Sitecore development as well maintenance.
Helix is most buzzed word you will hear nowadays. Most of the Sitecore solutions provider has adopted this standard principle while delivering new and all upcoming Sitecore Web Applications. It is little hard to move from the traditional development (vary by person to person) to Helix standards. But once you are familiar with the terms/Standards, Believe me – You will likely love it. There is a well written documentation on Helix, Habitat – An example solution based on Helix standards which you can refer as example of Helix, And there are many courses/presentation going on Helix.