The three-month emergency status gives the President and his Cabinet sweeping new powers that Erdogan says are aimed at tackling a looming "threat to democracy."
But rights groups and Western leaders have raised concerns that they will be used to achieve the exact opposite -- a rollback on democratic freedoms.
Here are the measures the government can legally impose in a state of emergency, according to a CNN examination of the law:
Restrictions on the public
Governments can impose curfews and declare certain public and private areas off limits, and it can ban or restrict meetings, gatherings and rallies.
A rally organized by the opposition secular Republican People's Party, (CHP), is planned for the weekend -- because the opposition actually supported Erdogan against the coup, the government's response to the rally is widely seen as a test of its commitment to democratic freedoms.
Government-backed security forces in a state of emergency do not need the usual authorization from a judge to search people.
Turkish Deputy Prime Minister Numan Kurtulmus said Thursday that the government planned to suspend the European Convention on Human Rights, the state-run Anadolu news agency reported.
The convention safeguards everything from the right to life, freedom from torture, the right to a fair trial and freedom of expression.
Political power shift
The state of emergency status will see a huge shift of power to Erdogan, who can take over all of the Prime Minister's responsibilities, should he wish to do so.
Instead of passing laws through the usually long parliamentary process, the Cabinet can create a draft decree, and with the President's approval, it will go to Parliament for a simple yes or no vote, to be made within 30 days.
The Constitutional Court in this period will be essentially stripped of its main function in overseeing the passage of laws. It will have no oversight of decrees in this period.
The power of Turkey's 81 provincial governors will also be increased in decision-making at the local level.
Press and NGO restrictions
The government or governors can ban the print and distribution of journals, magazines, newspapers, brochures, books and fliers in this period.
It can also restrict or ban any kind of audio-visual broadcast, whether it be television or radio news, or TV shows or movies.
A spokesman for Erdogan told CNN the state of emergency would not mean a crackdown on the media.
But before the state of emergency was declared, the government banned a magazine from printing its edition on the coup and it revoked the licenses of 24 broadcasters it said were linked to cleric Fethullah Gulen.
Erdogan and his government accuse Gulen of masterminding the coup and have requested his extradition from the United States, where he lives in self-imposed exile.
Amnesty International reported that at least 34 journalists had their press cards canceled.
'Threat to democracy'
One tool that could be used is the scrapping of appeals of court decisions, presidential spokesman Ibrahim Kalin told CNN in an interview, referring especially to civil servants.
"That is really the primary goal ... that these people, who have been involved in this coup attempt, and who killed people, murdered people basically on the street, will be put on trial without any chance of coming back to the state bureaucracy again."
Justice Minister Bekir Bozdag noted that the emergency move doesn't amount to "martial law" since the government is not "handing over the power to rule to the military."
"It is still in civilian hands," he said.
The move, Bozdag said on Thursday, was made "to get rid of the Fethullah Terror organization and its tentacles."
"In fact if our administration had the opportunity to take these steps without declaring a state of emergency then we would not have had to make this decision," he said.
Meanwhile, the opposition CHP is forming a commission to follow the judicial processes under the emergency to ensure that they are conducted fairly.
Ilhan Cihaner, a CHP lawmaker and a former prosecutor, will be part of the commission.
He was previously detained and tried under the sweeping Ergenekon trials a few years ago that targeted secularists suspected of devising anti-government plots.
Those trials are now widely viewed as being carried out by Gulenists who targeted people in the military, judciary, and police thought to be anti-Gulen, including Cihaner.
'Viruses" in the armed forces
Erdogan declared the state of emergency Wednesday night on national television, on the advice of the National Security Council and with approval by his Cabinet.
He guaranteed all "viruses" in the armed forces would be cleansed.
"It is very similar to a cancer," he said. "It is like a metastasis that is going on in the body that is Turkey. And we will clean it out."
Kurtulmus said the measures were in place "to fight against the parallel structure," according to Anadolu.
The government believes Gulen supporters have organized a parallel state, and uses the term "parallel structure" to refer to this alleged movement.
The Turkish Parliament on Thursday approved the state of emergency declaration by a 346 to 115 vote.
Erdogan's Justice and Development Party and Nationalist Movement Party lawmakers supported the measure. Parliament members from the CHP and the pro-Kurdish Peoples' Democratic Party opposed it.
Mass dismissals and arrests
The government has promised to respond to the attempted coup with a heavy hand, making mass arrests in what is increasingly looking like a well-planned witch hunt.
More than 50,000 people have been fired or suspended over the attempt to overthrow the government, including police, generals and admirals, teachers, judges and civil servants among others, and more than 9,000 remain in detention.
It has revived talks of the death penalty, imposed media restrictions, blocked websites and placed a ban on academics leaving the country.
Rights group Amnesty International warned that the country was abusing existing laws and that "the state of emergency gives them increased scope to continue on this dangerous path."
It explained that even if the European Convention on Human Rights were suspended, the country still had commitments under international law.
"Under international law, there are certain rights, like the right to a fair trial and bans on torture and discrimination, which can never be suspended or limited in any way," said Amnesty Turkey researcher Andrew Gardner.
The European Union regards the decisions on education, judiciary and the media as "unacceptable," EU High Representative Federica Mogherini and Commissioner Johannes Hahn said in a statement on Thursday.
"We call on Turkish authorities to respect under any circumstances the rule of law, human rights and fundamental freedoms, including the right of all individuals concerned to a fair trial," they said in the statement.
Officials from the United States, France and Germany have also reportedly warned Erdogan to act within the law.
U.N. Secretary-General Ban Ki-moon said Turkey must ensure due process for those accused of being involved in the coup. "The Secretary-General urges the Turkish authorities, consistent with the assurances given, to do their utmost to ensure that the constitutional order and international human rights law are fully respected, in line with Turkey's international obligations," he said in a statement.
At least 246 people were killed and more than 1,500 injured in the bloody violence that broke out on Friday night and continued Saturday, government officials say.
The death toll does not include the number of coup plotters killed, said to be 24 by various government officials.
The country will need a major restructuring of its security forces, having gutted the leadership of its military, with at least 118 generals and admirals detained, stripping the general-rank command of the Turkish military by a third, and suspending 8,777 Interior Ministry members, mostly police officers, state media reports say.