Graffiti writers practice varying styles: tagging, which is the most basic way to sign a name; throw-ups, which layer paint in one color and outline letters in another; blockbusters, or block letters; and wild style, a more elaborate style of letters blended with different colors.
City officials have spent millions to curtail traditional graffiti, and in gentrified and commercial areas it has declined along with other crime.
Street art flourishes in neighborhoods that are considered bohemian and trendy, whereas graffiti still shows up everywhere -- though less prominently in heavily policed places. Graffiti is most often found in poor and industrial areas, where it is less likely to be removed. But some graffiti writers say it's thrilling to tag a crowded touristy area like Times Square because the harder it is to paint, the more respect they earn.
Much of the public considers graffiti abrasive and difficult to decipher, but street art is often seen as aesthetically pleasing. Anyone caught doing either can be arrested for vandalism.
When street art begins to show up in a neighborhood, it is a sign that it is becoming safer for artists and outsiders to move in, said Jake Dobkin, who collects images for his website, streetsy.com. "That is the first step in the gentrification cycle."
The artists' presence attracts young professionals and middle-class people who want to live in trendy areas. Multimillion-dollar condos usually follow, pricing more people out of housing, and pushing them farther out into a widening halo around Manhattan.
Walking through Manhattan's Lower East Side, Ace Boon Kunle, 27, founder of a graffiti crew called Irak, talked of the transforming neighborhood, stopping at a brick building a few blocks east of one of the city's upscale neighborhoods, and a few blocks west of public housing projects. Its rooftop had his tag, "Earsnot," which he had spray-painted a decade ago. As he reminisced, construction workers tore down the building next door.
"They're going to turn this into a Candy Land-like playground for the wealthy," said Kunle, who recalled growing up and getting into trouble on the streets before they were overrun by cafes, bars and lofts.
He turned onto a narrow street. He spotted a black-and-white street art poster depicting a life-size shirtless man with a blurred face. The street artist had pasted the image over dozens of black, yellow and white graffiti tags.
Kunle walked toward the poster and splashed his hot tea over it.
IN the late 1990s, art school graduates Patrick McNeil and Patrick Miller moved to New York. The childhood friends from Arizona became fascinated by street art on the walls of Lower Manhattan.
Some images were abstract; others had undertones of activism and anti-capitalist messages. Street artists have replaced billboard images advertising iPods with dancing skeletons, or pasted Andre the Giant's face over a Starbucks logo. Others have altered signs inside train cars from "do not lean on door" to "do not fall in love," or turned the McDonald's Golden Arches into dripping streaks of slime.
With its roots in Europe, street art is often practiced by people who learned about it overseas, saw pictures online or noticed it on the streets of Manhattan and Brooklyn and wanted to try their own styles.
"They're not 16-year-old kids with a pen in their hand," said Marc Schiller, who runs woostercollective.com, which documents street art from around the world, and who organized an art-show tribute to the Spring Street building. "They are artists that really are interested in the city and they look at it as a canvas."
McNeil and Miller experimented with their own street art, calling themselves Faile. The pair's first images were of nude females, which they wheat-pasted in the middle of the night against the swirling backdrops of graffiti tags. They returned days later to discover the paper had ripped or crumbled in certain spots, sometimes adding precious details and character to the image.
"It was an art form that had a life," McNeil said. "It would transform into things that you didn't expect because of the weather and people interacting with it."
The two were arrested a few times, and like many beginning street artists, they did not understand that going over a tag could mean war. The artists, who have a studio in Brooklyn, are more careful now. They display less of their work on public walls, focusing instead on creating pieces on traditional canvases and other backgrounds to sell and display in art shows around the world.
They participated in the showcase at the Spring Street building, though they did not get upset when DYM and Irak crews tagged over the artists' work. They have not mourned the building's conversion into condos.
In New York, they said, nothing is permanent, nothing is precious -- that is part of its allure.
"Whether it's the art or whether it's the buildings, New York is constantly changing," McNeil said with a shrug. "Nothing stays the same."
"Same as the art," said Miller. "One day it's there, and one day it's not."