HONG KONG — Over the last month, protesters in Hong Kong have roiled the city with organized demonstrations that have used significantly different tactics than in the 2014 Umbrella Movement, when people blocked major roadways for weeks in a failed campaign for more open elections.

This year’s protests reached a boiling point on Monday, when hundreds of demonstrators broke into the building that housed the semiautonomous territory’s legislature.

From the march on July 1. Protesters charging the Legislative Council building. Lam Yik Fei for The New York Times

The events on Monday followed several large protests against a government proposed bill that would allow for the extradition of criminal suspects to mainland China, where the courts are controlled by the Communist Party.

Protesters have taken to the streets in record numbers, including marches attended by hundreds of thousands of people on June 16 and on Monday, which was the 22nd anniversary of the territory’s return to Chinese control.

On top of organized demonstrations, people have also taken to the streets in spontaneous gatherings. Protesters blocked roads and disrupted government services in response to anonymous calls in encrypted chat apps and online forums. Others have raised money online to pay for an international advertising campaign, including in The New York Times.

Things took a destructive turn on Monday when hundreds of protesters stormed the legislature, smashing windows and spray painting walls with political slogans.

Significant protests since June 9 Large demonstration Surrounded government headquarters, police responded with force Large demonstration General strike Surrounded police headquarters Blocked government buildings for taxation and immigration Raised $700,000 through crowdfunding for ad campaign Marched to consulates of G20 countries Large rally Surrounded police headquarters Surrounded Department of Justice Surrounded People’s Liberation Army dock Clashes near flag-raising ceremony Large demonstration Broke into Legislative Council building

JUNE 9 JUNE 12 N N Government headquarters Victoria Harbor HONG KONG Protesters occupied major roads in the area. Police responded with 150 rounds of tear gas. End Government headquarters Harcourt Rd. Victoria Park Start WAN CHAI CAUSEWAY BAY Lung Wo Rd. March route ADMIRALTY JUNE 16 N Protesters spilled onto other roads Victoria Park End Government headquarters Start WAN CHAI Official march route CAUSEWAY BAY ADMIRALTY JUNE 21 JUNE 24 Protesters blocked multiple government buildings. Protesters disrupted multiple government services again. Government buildings WAN CHAI Immigration Tower Police headquarters was surrounded for more than 15 hours. ADMIRALTY ADMIRALTY Revenue Tower Government headquarters Revenue Tower Government headquarters Immigration Tower 1 1 Harcourt Rd. was occupied for an hour. N N JUNE 26 N Circles represent consulates of G20 countries 2 8 p.m. Rally near city hall WAN CHAI 1 9 a.m. G20 consulates march 10 p.m. Blockade at police headquarters 3 U.S. consulate CAUSEWAY BAY ADMIRALTY Protesters surrounded the Legislative Council Complex during the day and broke into the building around 9 p.m. JUNE 28-29 JULY 1 N N Victoria Harbor Lung Wo Rd. Protesters clashed with police at a dock that was ceded to the People’s Liberation Army (PLA). Police fired tear gas around midnight to disperse protesters. Harcourt Rd. ADMIRALTY Government headquarters PLA building Some protesters went to the Legislative Council after the march. Some protesters continued forward. The planned march was peaceful. Hennessy Rd. Protesters surrounded this area. JUNE 9 JUNE 12 Government headquarters HONG KONG Victoria Harbor Protesters occupied major roads in the area. Police responded with 150 rounds of tear gas. Start Victoria Park Harcourt Rd. End Government headquarters WAN CHAI Lung Wo Rd. CAUSEWAY BAY ADMIRALTY March route N N JUNE 16 Start Victoria Park End Government headquarters Protesters spilled onto other roads WAN CHAI Official march route CAUSEWAY BAY ADMIRALTY N JUNE 21 JUNE 24 Protesters blocked multiple government buildings. Protesters disrupted multiple government services again. Government buildings WAN CHAI Police headquarters was surrounded for more than 15 hours Immigration Tower ADMIRALTY ADMIRALTY Revenue Tower Government headquarters Immigration Tower Revenue Tower 1 Government headquarters 1 Harcourt Rd. was occupied for an hour. N N JUNE 26 Circles represent consulates of G20 countries 2 8 p.m. Rally near city hall WAN CHAI 1 9 a.m. G20 consulates march U.S. consulate 10 p.m. Blockade at police headquarters 3 CAUSEWAY BAY ADMIRALTY N Protesters surrounded the Legislative Council Complex during the day and broke into the building around 9 p.m. JUNE 28-29 JULY 1 N N Victoria Harbor Lung Wo Rd. Protesters clashed with police at a dock that was ceded to the People’s Liberation Army (PLA). Police fired tear gas around midnight to disperse protesters. Harcourt Rd. ADMIRALTY Government headquarters Some protesters went to the Legislative Council after the march. PLA building The planned march was peaceful. Some protesters continued forward. Protesters surrounded this area. Hennessy Rd. JUNE 9 HONG KONG Victoria Harbor Start Victoria Park End Government headquarters WAN CHAI CAUSEWAY BAY ADMIRALTY March route N JUNE 12 Government headquarters Protesters occupied major roads in the area. Police responded with 150 rounds of tear gas. Harcourt Rd. Lung Wo Rd. N JUNE 16 Start Victoria Park End Government headquarters Protesters spilled onto other roads Official march route N Protesters blocked multiple government buildings. JUNE 21 Police headquarters was surrounded for more than 15 hours. Government buildings Immigration Tower Government headquarters 1 Revenue Tower Harcourt Rd. was occupied. N Protesters disrupted multiple government services again. JUNE 24 Immigration Tower ADMIRALTY Revenue Tower Government headquarters 1 N JUNE 26 8 p.m. Rally near city hall N 2 9 a.m. G20 consulates march 1 10 p.m. Blockade at police headquarters 3 JUNE 28-29 Protesters clashed with police at a dock that was ceded to the People’s Liberation Army (PLA). Government headquarters PLA building Protesters surrounded this area. N JULY 1 N Protesters surrounded the Legislative Council Complex during the day and broke into the building around 9 p.m. Police fired tear gas around midnight to disperse protesters. Harcourt Rd. Some protesters went to the Legislative Council after the march. Some protesters continued forward. Hennessy Rd. The planned march was peaceful. Satellite images by DigitalGlobe via Bing and Google Earth Studio

In the Umbrella Movement protests five years ago, thousands of pro-democracy demonstrators paralyzed key commercial districts in Hong Kong but ultimately failed to win concessions from the government.

“At the time, the people were stuck in a fixed place, which made it easier for the government to cope,” said Chung Kim-wah, a professor at the Hong Kong Polytechnic University, referring to the Umbrella Movement.

He noted that many of this summer’s protests were not planned ahead in the way they had been in 2014.

Some of the protests have been conventional, like Monday’s march that was organized by the Civil Human Rights Front, a pro-democracy group. The group has coordinated several recent marches that filled the streets in a display of the city’s anxiety about being ruled by mainland China.

But many of this year’s protests have had no clear leaders. Instead, people have organized collectively through social media and messaging apps. It is an approach that may be a direct response to the government’s crackdown on the Umbrella Movement’s leaders, several of whom were arrested and served prison terms.

The mainland and Hong Kong governments have called the protesters who stormed the Legislative Council “extreme radicals.” Some residents have questioned that group’s approach, but many pro-democracy lawmakers and groups have said they understood that frustration with the government’s response drove the protesters to adopt more forceful tactics.

“Everybody is understanding and sympathizing,” said Bonnie Leung, spokeswoman for the Civil Human Rights Front. “Some may condemn the violence, but they condemn the government more because they are the root cause.”

How Protesters Organized Themselves

In the movement this year, decisions on when, where and how to protest have often been made collectively and anonymously on the spot, or on social media platforms where users are anonymous and details are worked out through likes and so-called upvotes.

The movement uses LIHKG, an online forum similar to Reddit, where users post calls to action, and the most popular ones get pushed to the top of the forum.

Protesters have also become more agile and mobile by using Telegram, an encrypted messaging platform, to create public channels to share information and smaller private groups to quickly organize actions.

An example of how online channels are used by protesters

LIHKG Online forum A post suggesting protesters disperse got more than 10,000 votes. Telegram Messaging app A chat group that shares protest information held a poll on whether or not to stay. Note: Offensive language has been grayed out.

Eric Siu, one of the participants at the G-20 protests on June 26, described how users create discussion threads on LIHKG and provide suggestions. “Then people will give responses or click push to make that specific thread a hot one,” he said. “We can predict what’s going to happen by which posts are the hottest.”

This tactic has also allowed protesters to move quickly from location to location, sometimes without much advance planning. Benny Yap, a car dealership owner, has been voluntarily delivering supplies to protesters and figures out where they are by checking the LIHKG forum. During the Umbrella Movement, he would simply show up at government offices where protesters had set up tents.

Images shared on a local social media site called for protests and other actions

Images via LIHKG

Advertisements that ran in newspapers in different countries through a crowd-funded campaign

Images via Twitter

The Civil Human Rights Front, which organized recent marches, has now also taken on a new role, providing support for acts of civil disobedience initiated by the online groups whenever needed.

“The whole campaign is full of energy and new ideas,” said Ms. Leung. “All these events are things that traditional political groups wouldn’t have done.”