The Men of the Lake (also known as Lake-Men) were a group of Men closely related to the Men of Dale, and distantly related to the Edain, who dwelt in and around Esgaroth during the time of the War of the Ring. As such, they spoke a language distantly related to the Common Speech. And like the Men of Dale, the Lake-Men could speak with the thrushes.
The Men of Lake-Town originally dwelt on the shores of the Long Lake, but after the town fell to ruin, it was rebuilt on stilts upon the lake. Unlike their cousins in Dale, the Lake-Men did not have a King, but instead elected a Master.
When Smaug destroyed the town of Dale in 2770 Third Age, many of the inhabitants went south and added to the numbers of the Lake colony. Smaug was eventually killed by Bard – the descendant of King Girion of Dale – who shot the dragon through a weak spot in his underbelly with a Black Arrow; Esgaroth was destroyed in the process.
Dale and Erebor were refounded after the destruction of Smaug, and though the men of Lake-Town continued to elect their own Masters for a time, the town eventually seemed to become part of the expanding kingdom of Dale.