The common thread among the thousands of people from around the globe is celebrating the Illawarra's history.

Starting out last May, the Facebook site Lost Wollongong has grown to become the region's largest online heritage community forum.

The project started when David Bottin approached friend and fellow history buff Brenden Brain with the idea of creating a Facebook forum similar to groups operating out of Sydney and Newcastle.

"I figured that given the Illawarra's proud history, from the first Australians to the early European settlers, agriculture, mining and heavy industry, there would be plenty of locals and expats who would not only be interested in learning more about our region's history, but would be keen to share their memories and photos with others," Mr Bottin said.

Mr Bottin said not only did the region embrace the Facebook page, membership has since eclipsed its older neighbouring counterparts.

In just 12 months, members had contributed to a catalogue of 15,000 photos, many submitted from private collections and others supported by Wollongong Library's Local Studies Unit.

One member, Kerry Whitehead, found her own six degrees of separation through Lost Wollongong. She has reconnected with Sue Williams (Mrs Whitehead's second cousin), Cathie Potter (a primary school friend from St Columbkille's Corrimal), Dianne Cordin (a next-door neighbour from the late 1950s), Margaret Chandler (a long-time friend), Mick Davies (with whom she is distantly related) and Allan Baker (who went to primary school with Mrs Whitehead's husband).

Lost Wollongong also has a new website here and has been launched on Twitter and Instagram.