What is the green line?

The green line is the truce line declared at the end of the 1948 war. The lines agreed between Israel and Lebanon, Syria, Jordan and Egypt between February and July1949. The lines were based on the location of the forces on the ground, the UN partition plan into Arab and Jewish states, and the internationalization of Jerusalem declared on 29/11/1947 and other interests that arose during the negotiations.

On June 1967 Israel conquered territories from Egypt, Jordan and Syria, pushing the borders away. The green line borders were kept with Lebanon and restored with Egypt after the peace treaty of 1978. The peace treaty between Israel and Jordan (1994) was based on the green line north from Beit-Shean and south from Ein-Gedi. Israel had annexed unilaterally parts of the territories beyond the green line in east-Jerusalem and the Golan-heights.

More information available in the following links. Please note that this a politically loaded issue and some information might be biased.

http://en.wikipedia.org/wiki/Green_Line_(Israel)

http://en.wikipedia.org/wiki/1949_Armistice_Agreements

http://en.wikipedia.org/wiki/United_Nations_General_Assembly_Resolution_181