Amid rising anticipation of a US-Israeli agreement on a settlement freeze, Israeli Prime Minister Benjamin Netanyahu and US envoy George Mitchell said they would meet again Wednesday after an inconclusive visit Tuesday in Jerusalem.

With one week until the United Nations General Assembly opens in New York, the contested issue has taken on new urgency. President Barack Obama, whose administration has strongly encouraged a settlement freeze as a way to jumpstart Arab-Israeli peace talks, seeks to meet Mr. Netanyahu and Palestinian leader Mahmoud Abbas on the sidelines of the UN gathering. But Mr. Abbas has refused to resume negotiations before Israel agrees to a total freeze.

Netanyahu, under pressure from his right-wing constituents not to succumb to Washington's demands, last week approved permits for 455 new housing units to be built in the settlements – bringing to nearly 3,000 the number of homes his government would likely exclude from any settlement freeze.

Originally encouraged by the government after Israel expanded its territory in the 1967 war with its Arab neighbors, settlements were meant to seed Israeli "pioneers" and to extend the Jewish state's defenses. Now numbering 121, their purpose and legality draw varying definitions and fuel relentless debate.

This Monitor briefing examines those definitions, explains the varying interpretations of international law, and looks at the trends in settlement growth over the past few decades.

What is a settlement?

A settlement is any residential area built over the Green Line, the 1949 cease-fire line established between the newly established Jewish state and its Arab neighbors. Today, Israelis live in several key areas that Israel took control of in the 1967 Six-Day War: the West Bank, East Jerusalem, and Syria's Golan Heights.

As a key part of his Middle East policy, President Barack Obama has insisted that Israel freeze settlement expansion as a confidence-building gesture to help relaunch Middle East peace talks. Palestinian Authority President Mahmoud Abbas has said he will not commence negotiations with the government of Prime Minister Benjamin Netanyahu unless he halts settlement growth first. Arab governments have also made a withdrawal to 1967 borders a prerequisite to making peace with Israel.

The main focus is on settlements in the West Bank, where Israeli pockets give the mainly Palestinian territory a Swiss-cheese look (see map). Palestinians and their supporters describe settlements as "facts on the ground" that will force the hand of future negotiators determining the borders of a Palestinian state.

How many are there?

From 30 in the early 1970s, West Bank settlements now number 121, and the settler population there this year surpassed 300,000. An additional 17,000 Israelis live in the Golan Heights and 193,000 in East Jerusalem, where Palestinians hope to establish the capital of their future state. (Israel annexed East Jerusalem in 1980 and thus does not consider citizens there settlers, but most international and human rights organizations do.)

Formerly, 8,000 settlers lived in the Gaza Strip, but they were evacuated in 2005 under former Prime Minister Ariel Sharon's disengagement plan. According to figures from Israel's Central Bureau of Statistics and the Foundation for Middle East Peace (FMEP) in Washington, the settler population in the West Bank and Gaza has increased three times faster, on average, than the population within Israel proper since the 1993 Oslo peace accords were signed. Last year, the growth rate was 4.9 percent in the West Bank compared with 1.8 percent in Israel.

Who lives there?

After the 1967 war, Israeli governments – left and right – promoted settlements as a strategy to strengthen Israel's defense and protect it from further attacks from neighboring Arab countries. Proponents encouraged Israelis to go to the fledgling communities as "pioneers."

Most eager were national-religious activists known as "Gush Emunim" or Bloc of the Faithful. These settlers believed that Israel's success in the 1967 war was a sign of messianic redemption, and today they view the settler movement as an irreversible return of the Jewish people to their biblical homeland.

But while many have moved for patriotic or religious reasons, other settlers seek a different lifestyle – wanting to live in a small, semirural community, or in the desert. Some are also motivated by financial considerations. For example, a 968-square-foot apartment in Jerusalem's upper-middle-class Arnona neighborhood is advertised at $385,000, while a 1076-square-foot apartment in the burgeoning settlement of Maale Adumim just a 10-minute drive away can be bought for $186,000. While most government incentives for settlers, such as grants and tax breaks, were eliminated under Mr. Sharon, Israelis can often still obtain more advantageous mortgages for homes in settlements.

Since the Oslo Accords, Israel has also ramped up construction of roads serving settlements. Many are only intended to service settlements and not neighboring Palestinian villages. Btselem, an Israeli rights group, says that some of these new roads are forbidden to Palestinian traffic.

Are they illegal?

The United Nations considers the West Bank, East Jerusalem, and the Golan Heights occupied territory; Israel considers them territories under its administration and officially refers to the West Bank by the biblical names Judea and Samaria. Much of the international community also does not recognize Israel's annexation in 1967 of the Golan Heights and East Jerusalem, which it declared its "complete and united" capital.

Palestinians and many international organizations say that on the basis of the Fourth Geneva Convention, the settlements are a serious violation of international law. Article 49 says that the occupying power "shall not deport or transfer parts of its own civilian population into the territory it occupies." Israel holds that the West Bank, East Jerusalem, and the Golan Heights are territories acquired in a defensive war, and that Geneva conventions are not applicable to the dispute: Settlers have not been moved there by force nor transferred en masse. Israel also says that the transfer of major West Bank cities to Palestinian Authority control means that the area should no longer be considered occupied.

There are settlements that Israeli officials do consider to be illegal, however. Known as outposts, they are established without any government permission, usually on the fringes of larger settlements. Peace Now, an antisettlement group, counts 100 outposts. Around 50 were established after March 2001, when Sharon came to office and promised the US he would stop the growth of outposts, according to a government-commissioned study known as the Sasson Report. Among these, 24 are on a list of illegal settlement outposts scheduled to be dismantled by the Israeli government.

What obligations does Israel have?

The previous two Israeli prime ministers – Sharon and Ehud Olmert – promised to remove those 23 outposts in talks with the Bush administration. Mr. Netanyahu has repeated that pledge.

Since coming to power in March, the Netanyahu government put a de facto freeze on issuing tenders for new housing in the settlements until Sept. 6, when it approved permits for an additional 455 units. The approximately 2,500 issued previously would allow developers to move ahead once they are ready – potentially increasing by tens of thousands the number of housing units under construction in the West Bank and East Jerusalem, which currently stands at 1,000, according to Peace Now. Moreover, government-sponsored construction constitutes about 40 percent of all construction in the territories, Peace Now says, with the rest funded by private initiatives and settler groups.