Palestinian prisoners have engaged in mass hunger strikes since 1968, after Israel occupied the Palestinian territories.

After 40 days of fasting, approximately 1,500 Palestinian political prisoners announced the end of their hunger strike for basic rights in Israeli jails on Saturday.

On April 17, Palestinian Prisoners Day, the prisoners embarked on the dangerous journey of an open-ended fast to pressure Israel - which is responsible under international law for the well-being of all persons in its custody - to improve prison conditions. The prisoners survived on salt water only.

Healthy humans can survive up to eight weeks without food, but the risk of starvation differs from one person to another depending on body weight, genetics and other factors.

The prisoners' demands were simple. They included the installation of a public telephone to communicate with their families, reinstating bimonthly family visits, better medical treatment, allowing prisoners to take photographs with their families regularly, and installing air conditioning where lacking.

They also called on Israel to end its policy of administrative detention, which allows the imprisonment of individuals on "secret evidence" for months and years on end, and to end its excessive use of solitary confinement, which is in direct contravention of international law.

A deal was said to have been reached with Israeli authorities for better conditions, but no details have been made public yet.

Under international human rights law, prisoners must be guaranteed basic human rights, which include the right to maintain a family life and freedom from torture and other forms of CIDT (cruel, inhuman or degrading treatment).

Since 1967, 72 Palestinian political prisoners have died as a result of torture by Israeli prison authorities, according to Jerusalem-based prisoners' rights group Addameer.

READ MORE: What it means to be a Palestinian prisoner in Israel

"Israel's responsibility … is supposed to be even greater towards prisoners because incarceration is a condition that exposes the incarcerated person to violations of his/her rights to a greater degree than with non-incarcerated citizens and residents," Ran Yaron, a spokesperson for Physicians for Human Rights in Israel, told Al Jazeera.

Palestinians have launched and engaged in mass hunger strikes as far back as 1968 after Israel occupied the remaining Palestinian territories of the West Bank, East Jerusalem and the Gaza Strip. Some strikes have been regarded as successful, while others were seen to have failed to reach their goals.

Several Palestinian administrative detainees have also gone on individual hunger strikes and have managed to pressure Israel into releasing them, although some have been rearrested.

Though in some cases Israeli prison authorities agreed to negotiate with prisoners on improving conditions, they more often than not respond by placing the prisoners in solitary confinement, transferring them between prisons and blocking family visits.

From the 1980s onwards, prison authorities resorted to force-feeding prisoners on hunger strike using a nasal tube, which resulted in the death of several Palestinians.

The United Nations Committee Against Torture has called on Israel to ensure that prisoners on hunger strike are not subjected to force-feeding or other medical treatment against their will, as it could amount to torture. UN experts have also said the practice "under no circumstance will ... comply with human rights standards".

Hunger strikes have taken place elsewhere throughout history as a method of nonviolent resistance. By drawing international attention to the plight of prisoners, they aim to put pressure on their jailers and spur a change in policy.

The tactic was used by British and American suffragettes in the early 20th century, Irish republicans, and most notably, Mahatma Gandhi, among many others. Under international human rights norms, hunger striking is seen as a form of freedom of expression and a civil and political right.

Al Jazeera compiled a timeline of notable mass hunger strikes in Palestinian history and looked at what has been achieved.