Since a longstanding taboo on criticising Thailand's monarchy was broken by protesters in early August, their rallies in Bangkok have got increasingly bold in criticising King Maha Vajiralongkorn and demanding change.
HOW DID THE PROTESTS START?
Anti-government protests emerged last year after courts banned the most vocal party opposing the government of former junta leader Prayuth Chan-ocha.
After a pause during measures to stop the spread of the coronavirus, protests resumed in mid-July - pushing for Prayuth's removal, a new constitution and an end to the harassment of activists.
Some protesters went further with a list of 10 demands to reform the monarchy.
Protesters say they do not seek to end the monarchy, only reform it, but conservatives are horrified by such attacks on an institution the constitution says is "enthroned in a position of revered worship".
Prayuth has said that while protests should be allowed, criticising the monarchy goes too far.
WHAT DOES THE PALACE SAY?
The Royal Palace has made no comment on the protests and the demands for reform despite repeated requests.
WHAT REFORMS DO THE PROTESTERS WANT?
Not all protesters demand reform of the monarchy, with some saying such calls are counterproductive, but the size of the weekend demonstrations showed the scale of support.
Protesters want to reverse a 2017 increase in the king's constitutional powers, made the year after he succeeded his widely revered late father King Bhumibol Adulyadej.
Pro-democracy activists say Thailand is backtracking on the constitutional monarchy established when absolute royal rule ended in 1932. They say the monarchy is too close to the army and argue that this has undermined democracy.
Protesters also seek the scrapping of lese majeste laws against insulting the king. They want the king to relinquish the personal control he took over a palace fortune estimated in the tens of billions of dollars, and some units of the army.
WHY ELSE ARE THEY UNHAPPY?
Protesters complain that the king endorsed Prayuth's premiership after elections last year that opposition figures say were engineered to keep his hands on power. Prayuth, who as army chief led a 2014 coup, says the election was fair.
Protesters have voiced anger that the king spends so much of his time in Europe.
They have also challenged the spending of the Palace and lifestyle of the king, who has been married four times and last year took a royal consort.
WHAT IS THE SIGNIFICANCE OF THE PLAQUE?
Protesters cemented a brass plaque on the Sanam Luang - or Royal Field - near the Grand Palace. The plaque proclaims that Thailand belongs to the people, not the monarch.
It resembles one commemorating the end of absolute monarchy removed without explanation from outside one of the royal palaces in 2017, the year after Vajiralongkorn took the throne, and replaced by one with a pro-monarchist slogan.
WHAT DO THE LESE MAJESTE LAWS MEAN?
The Thai monarchy is protected by Section 112 of the country's Penal Code, which says whoever defames, insults or threatens the king, queen, heir-apparent or regent shall be jailed for three to 15 years.
In June, Prayuth said the law was no longer being applied because of "His Majesty's mercy". The Royal Palace has never commented on this.
Rights groups say opponents of the government - including more than a dozen of the protest leaders - have recently been charged under other laws such as those against sedition and computer crimes.
The government has said it does not target opponents but it is the responsibility of the police to uphold the law.