In the late 19th century Zionism arose as a nationalist and political movement aimed at restoring the land of Israel as a national home for the Jewish people. Tens of thousands of Jews, mostly from Eastern Europe but also from Yemen, started migrating to Palestine (called Aliyah, "going up"). Zionism saw national independence as the only answer to anti-Semitism and to the centuries of persecution and oppression of Jews in the Diaspora. The first Zionist congress took place in 1897 in Basel under the guidance of Austrian journalist Theodor Herzl, who in his book "The Jewish State" had painted a vision of  a state for the Jewish people, in which they would be a light unto the nations. Zionism basically was a secular movement, but it referred to the religious and cultural ties with Jerusalem and ancient Israel, which most Jews had maintained throughout the ages. Most orthodox Jews initially believed that only the Messiah could lead them back to the 'promised land', but ongoing pogroms and the Holocaust made many of them change their minds. With the number of jews in israel growing this began to breed tensions with the Palestinians and other arabs in the area.
During World War I Great Britain captured part of the Middle East, including Palestine, from the Ottoman Empire. In 1917 the British had promised the Zionists a 'Jewish national home' in the Balfour Declaration, and on this basis they later were assigned a mandate over Palestine from the League of Nations. The mandate of Palestine initially included the area of Transjordan, which was split off in 1922 (see map).
Jewish immigration and land purchases met with increasing resistance from the Arab inhabitants of Palestine, who started several violent insurrections against the Jews and against British rule in the 1920s and 1930s. During the Great Revolt of 1936-1939 the followers of the radical Mufti of Jerusalem Haj Amin al-Husseini (a Nazi collaborator who later fled the Nurnberg Tribunal) not only killed hundreds of Jews, but an even larger number of Palestinian Arabs from competing groups. The Zionists in Palestine (called the Yishuv) established self-defense organizations like the Haganah and the (more radical) Irgun. The latter carried out reprisal attacks on Arabs from 1936 on. Under Arab pressure the British severely limited Jewish immigration to Palestine, after proposals to divide the area had been rejected by the Palestinian Arabs in 1937. Jewish refugees from countries controlled by Nazi Germany now had no place to flee to, since nearly all other countries refused to let them in. In response Jewish organizations organized illegal immigration (Aliya Beth), the Zionist leadership in 1942 demanded an independent state in Palestine to gain control of immigration (the Biltmore conference), and the Irgun committed assaults on British institutions in Palestine.
Despite pressure from the USA, Great Britain refused to let in Jewish immigrants - mostly Holocaust survivors - even after World War II, and sent back illegal immigrants who were caught or detained them on Cyprus. Increasing protests against this policy, incompatible demands and violence by both the Arabs and the Zionists made the situation untenable for the British. They returned the mandate to the United Nations (successor to the League of Nations), who hoped to solve the conflict with a partition plan for Palestine, which was accepted by the Jews but rejected by the Palestinians and the Arab countries. The plan proposed a division of the area in seven parts with complicated borders and corridors, and Jerusalem and Bethlehem to be internationalized (see map).  The relatively large number of Jews living in Jerusalem would be cut off from the rest of the Jewish state by a large Arab corridor. The Jewish state would have 56% of the territory, with over half comprising of the Negev desert, and the Arabs 43%. There would be an economic union between both states. It soon became clear that the plan could not work due to the mutual antagonism between the two peoples. After the proposal was adopted by the UN General Assembly in November 1947, the conflict escalated and Palestinian Arabs started attacking Jewish convoys and communities throughout Palestine and blocked Jerusalem, whereupon the Zionists attacked and destroyed several Palestinian villages. The Arab League had openly declared that it aimed to prevent the establishment of a Jewish state
A day after the declaration of the state of Israel (May 14, 1948) Arab troops from the neighboring countries invaded the area. At first they made some advances and conquered parts of the territory allotted to the Jews. Initially they had better weaponry and more troops, but that changed after the first cease-fire, which was used by the Zionists to organize and train their newly established army, the Israeli Defense Forces. Due to better organization, intelligence and motivation the Jews ultimately won their War of Independence.
With this independence of a Jewish state there were many displaced Arabs. The Neighboring Arab countries Arab countries refused to permanently house the Palestinian Arab refugees, because they - as well as most of the refugees themselves - maintained that they had the right to return to Israel. About a million Palestinian refugees still live in refugee camps in miserable circumstances. Israel rejected the Palestinian 'right of return' as it would lead to an Arab majority in Israel, and said that the Arab states were responsible for the Palestinian refugees. Many Palestinian groups, including Fatah, have admitted that granting the right of return would mean the end of Israel as a Jewish state. The question of the Palestinian right of return is the first mayor obstacle for solving the Arab-Israeli? conflict.
The Arab-Israeli? conflict persisted as Arab countries refused to accept the existence of Israel and instigated a boycott of Israel, while they continued to threaten with a war of destruction. (There were some talks, but the Arab states all demanded both the return of the refugees and also parts of Israel in return for just non belligerence). They also founded Palestinian resistance groups which carried out terrorist attacks in Israel, like Fatah in Syria in 1959 (under the guidance of Yasser Arafat), and the PLO in Egypt in 1964.
In May of 1967, the conflict escalated as Egypt closed the Straits of Tiran for Israeli shipping, sent home the UN peace keeping force stationed in the Sinai, and issued bellicose statements against Israel. It formed a defense union with Syria, Jordan and Iraq and stationed a large number of troops along the Israeli border. After diplomatic efforts to solve the crisis failed, Israel attacked in June 1967 and conquered the Gaza Strip and the Sinai Desert from Egypt, the Golan Heights from Syria and the West Bank and East Jerusalem from Jordan (see map below). Initially Israel was willing to return most of these territories in exchange for peace, but the Arab countries refused
After 1967 the focus of the Palestinian resistance shifted to liberating the West Bank and the Gaza Strip as a first step to the liberation of entire Palestine, and ultimately sovereignty. The Arab Palestinians started to manifest themselves as a people and to demand a nation state and self determination. East Jerusalem, reunited with West Jerusalem and proclaimed Israel's indivisible capital in 1980, but also claimed by the Palestinians as their capital, became a core issue for both sides in the conflict. The division of Jerusalem with its holy places is the second large obstacle for a solution to the Arab-Israeli? conflict.
A second war in the arab israeli conflict was the Yom Kippur War.
On October 6, 1973 — Yom Kippur, the holiest day in the Jewish calendar — Egypt and Syria opened a coordinated surprise attack against Israel. The equivalent of the total forces of NATO in Europe were mobilized on Israel's borders. On the Golan Heights, approximately 180 Israeli tanks faced an onslaught of 1,400 Syrian tanks. Along the Suez Canal, 436 Israeli defenders were attacked by 80,000 Egyptians.

At least nine Arab states, including four non-Middle Eastern nations, actively aided the Egyptian-Syrian? war effort.
A few months before the Yom Kippur War, Iraq transferred a squadron of Hunter jets to Egypt. During the war, an Iraqi division of some 18,000 men and several hundred tanks was deployed in the central Golan and participated in the October 16 attack against Israeli positions. Iraqi MiGs? began operating over the Golan Heights as early as October 8, the third day of the war.
Thrown onto the defensive during the first two days of fighting, Israel mobilized its reserves and eventually repulsed the invaders and carried the war deep into Syria and Egypt. The Arab states were swiftly resupplied by sea and air from the Soviet Union, which rejected U.S. efforts to work toward an immediate cease­fire. As a result, the United States belatedly began its own airlift to Israel. Two weeks later, Egypt was saved from a disastrous defeat by the UN Security Council, which had failed to act while the tide was in the Arabs' favor.
Since the 6 Day war and Yom Kippur war there have been other confrontations between the two sides including: The first and second Israel-Lebanon? War(1982 and 2006), The intifada of uprising of the plantains in late 80s early 90s and again from 2000-2006, and many skirmishes between the Israelis and Palestinians.
In 2005 Israel withdrew from Gaza in hope of reducing the tension between the two sides. The "Disengagement Plan" was announced in December 2003, Prime Minister Ariel Sharon said the withdrawal was to increase security of residents of Israel, relieve pressure on the Israeli Defense Forces (IDF) and reduce friction between Israelis and Palestinians. Hamas, the Islamic Resistance Movement, claims that the withdrawal is the result of violent Palestinian resistance to Israeli occupation. On Aug. 15, 2005 tens of thousands of Israeli troops oversaw the evacuation of the settlers from 21 different communities in Gaza and four smaller settlements in the West Bank. Some Palestinian security forces will also participated in this withdrawl. On Aug. 17, 2005 the settlers that did not voluntarily leave had to be forcibly removed and may lost personal property, according to IDF commanders. Israeli soldiers then demolished settlers' homes. This gave the Palestinians a land free from Israeli control, and gave them sovereignty over their own ports, airspace and people.
Tensions in Israel are constantly continuing. This is attributed to many reasons but one is uneven development. Israel is developing very quickly and have a relatively low birthrate. Apposed to the Palestinians who have a very high birth rate and thus NIR, this showing how much less developed they are. This development gap only breeds more tension between the two sides. As the number of Palestinians grows and Gaza become more and more dense further conflict is inevitable.