Probably one of the spider genera best known to humans is the pholcid genus Pholcus. Commonly known as daddy-longlegs or cellar spiders, many species from this genus are synanthropic and often share our houses with us. Daddy-longlegs are even important characters in children's tales such as The Tale of Daddy-longlegs by Scott Arthur Bailey. However in some places "daddy-longlegs" is used when referring to harvestmen (Opiliones).

Pholcids show very high ecological plasticity and can be found everywhere, from deserts to humid tropical forests. Similar to many other arthropod groups the pholcids are most diverse in the tropical regions of the world. Several studies have shown that pholcids might be among the commonest if not the dominating web builders in some tropical regions (Manhart, 1994; Huber, 2000, 2003a). Currently there are 85 genera and 1000 species (Platnick, 2009) of pholcids but recent evidence shows that most of the diversity of this group is still unknown (Huber, 2000, 2003a, 2003b, 2003c, 2005a, 2005b, 2007).