'Auto flowering' means that the plant will not require the trigger of 12/12 light cycle to kick it into flowering. This means that the plant will 'automatically' move into flowering mode after a short veg period of around 3 weeks. The big advantage is that you keep them growing start to finish on a 18/6 cylcle and they will just flower away! You can add new plants for a perpetual turnover without the need for seperate cabinets etc!
Yields are not the biggest, but Lowryder for example stays short and compact. The strains are Indica/sativa/ Ruderalis and it is the latter which brings the autoflowering trait through.
More info on the Joint Doctors site, creator of the Lowryder strains.
http://www.lowryder.co.uk/en/about-seedsman/weed-world-article