The Lower East Side is a composite neighborhood of the New York City borough of Manhattan which consists of the neighborhoods of the East Village; Chinatown; Little Italy; Tompkins Square; Astor Place; and the housing development known as "Knickerbocker Village" at Corlears Hook It has traditionally been an immigrant, working class neighborhood, but it has undergone gentrification in recent years and is increasingly populated by young professionals, artists, students and hipsters. While the exact boundaries of the neighborhood are open to debate, it today refers to the area of Manhattan south of East 14th Street; north of Fulton Street and Franklin Street; east of Pearl Street and Broadway; and west of the East River.

The Lower East side is bordered in the south and west by Chinatown (which extends north to roughly Broome Street), in the west by NoLIta and in the north by East Village.

East Village was once Lower East Side's northwest corner alongside Greenwich Village; it received that name from real estate developers in the 1980s trying to dissociate the area from the Lower East Side's reputation. The name stuck and the term "Lower East Side" now refers specifically to the portion of the neighborhood lying south of Houston Street and East Village has become its own separate neighborhood.

In the early 2000s, the gentrification of the East Village spread to the Lower East Side, making it one of the trendiest neighborhoods in Manhattan. Clinton Street and Orchard Street are lined with upscale restaurants and boutiques, although Orchard Street is still dominated by discount clothing stores.

In late 2004, a boutique hotel, The Hotel on Rivington, or THOR, opened on Rivington Street. The glass-walled, 22-storied hotel towers over the neighborhood and provides a sharp contrast to the surrounding low-rise brick tenements.

In recent years, the gentrification that was previously confined to north of Delancey Street has continued south. Several restaurants, bars and galleries have opened below Delancey Street since 2005, especially around the intersection of Broome and Orchard Streets. The neighborhood's second boutique hotel, Blue Moon Hotel opened on Orchard Street just south of Delancey Street in early 2006. However, unlike THOR, the Blue Moon used an existing tenement building and its exterior is almost identical to neighboring buildings.

As the neighborhood gentrified and has become safer at night, it has become a popular late night destination. Clinton Street and Ludlow Street between Rivington Street and Stanton Street become especially packed at night, and the resulting noise is a cause of tension between bar owners and longtime residents.

Also, the Lower East Side is home to many live music venues. Up and coming alternative rock bands play at Bowery Ballroom on Delancey Street and Mercury Lounge on East Houston Street, while lesser known bands play at Tonic on Norfolk Street and Rothko on Suffolk Street. There are also bars that offer performance space, such as Pianos and the Living Room on Ludlow Street.