Welcome to Eid-ul-Fitr
"When you see the crescent (of the month of Ramadan), start fasting, and when you see the crescent (of the month of Shawwal), stop fasting; and if the sky is overcast (and you can't see it) then regard the month of Ramadan as of 30 days." (Sahih Bukhari Hadith 3.124)
The festival of Eid-ul-Fitr marks the end of the season of Ramadan and the beginning of the month of Shawwal. It is a time of great celebration for Muslims as it means that the long fast is over and life can return to normal. The festivities last for four days.
As the prophet Muhammad (pbuh) said:
"A fasting person will have joy and happiness twice; when he breaks the fast he will be full of joy because it is at an end, and when he meets his Lord on the Day of Judgement, because he has kept his obligation." (cited in Cole with Morgan 1995 edition)
In other words, there are two reasons for celebrating Eid-ul-Fitr. The first is to thank Allah for the courage and strength to survive the fast. The second because it is a sign of obedience to him. As well as this, Muslims celebrate Eid-ul-Fitr because they use it as the time of the year when they can celebrate all that is good about family life. No one is forgotten; even the dead are visited in their graves to show that they are still appreciated by their loved ones.