There are several species of grasses suitable for growing in domestic lawns in the UK (England/Scotland/Ireland).
Different grass species can be mixed to control the coarseness/fineness and durability of the lawn. When you purchase grass seed from a garden centre, DIY store or high street shop, the seed mix is usually a blend of different grasses that have been specifically selected for their suitability for domestic lawns in the most common situations, such as General Purpose Utility, Luxury Grade, Shade Tolerant or drought tolerant. If you are laying turf rather than seeding a lawn you will find that there is usually not such a wide choice of grass types available.
General purpose hard wearing lawns, that don't require excessive mowing and need to look their best under constant use, require dense, compact and richly coloured grasses, with the ability for good wear and persistency.
A common seed mixture for hard wearing utility lawns is a mix of fine leaved grasses such as Bents and Fescues with one or more courser species such as a Perennial Ryegrass or a Meadow Grass. Such mixtures are usually fast growing and need regular mowing.
For good quality lawns the grass variety should contain fine-leaved species that will produce uniform growth and colour and be able to thrive under close and frequent mowing.
A typical seed mixture for high quality ornamental lawns will consist entirely of fine-leaved dwarf grasses such as Bents and Fescues. This type of blend is slow growing and can usually be mown very short.
This is type of lawn is mainly for show, by enthusiasts who want a finely kept and well manicured lawn. Such luxury lawns require regular mowing and routine management and will not stand up well to prolonged hard wear. Ornamental lawns are the most expensive to establish and maintain as they need extensive site preparation and constant maintenance.
Species that will grow well in low light and have a good drought resistance are essential for shaded areas that receive little sun and often little rain.
A good blend for shaded lawns is a mix of fine leaved and creeping Fescues. The resulting lawn should be drought tolerant but is usually not very hard wearing.
Ref 1: Dr. D. G. Hessayon. The New Lawn
Expert. Expert Books. 1997.
Ref 2: Pamela Brown et al. RHS Lawns & Ground Cover. Dorling Kindersley. 1999.