Palestinians have taken control of the Rafah border, the only crossing point between the Gaza Strip and Egypt.
It is the first time Palestinians have been given control of an international border and gives Gaza residents their first access to the outside world in almost three months.
Palestinian officials hope a fully functioning border will help kick start a desperately depressed economy and help bring down unemployment that has soared to almost 40% in recent months.
The crossing will initially operate for four hours a day. It will run under Palestinian and Egyptian management and will be supervised by 70 EU observers.
Israel withdrew its forces from the Gaza Strip in September after 38 years of occupation.
It had long refused to reopen the border, citing fears that weapons could be smuggled from Egypt into Gaza - a stronghold of militant factions such as Hamas and Islamic Jihad.
The border was officially opened by Palestinian President Mahmoud Abbas.
