Megillat Eicha (Lamentations) is one of the five megillot (scrolls) in Ketuvim, the last part of Tanach, the written Torah. It mourns Yerushalayim (Jerusalem) and the first Beit HaMikdash (Holy Temple), destroyed by the army of Bavel (Babylon), and the people of Yehudah (Judah), who were killed, starved or carried into galut (exile). The Gemara says that Yirmiyahu (Jeremiah) the navi wrote it. Its name is its first word, eicha (how), a cry of disbelief at how far the city has fallen.
Eicha is read on the night of Tisha B'Av, the ninth of Av, the fast day on which we mourn the destruction of both Batei HaMikdash (Temples). It is leined in its own sad tune, and the custom is for the congregation to sit on the floor or on low seats, as mourners do. In some communities it is read again on the morning of Tisha B'Av (usually after Shacharit, the morning prayer).
The megillah has five perakim. Four of them are alphabetical: each pasuk (verse) of perakim 1, 2 and 4 begins with the next letter of the alef-bet, and perek 3 gives three pesukim to each letter, 66 in all. Perek 5 also has 22 pesukim, but it does not follow the letters.
Perek 1 shows Yerushalayim alone, like a widow, with no one to comfort her, and then lets the city speak of her own pain. Perek 2 describes Hashem's anger: He Himself has torn down the walls, the palaces and the Mikdash, while children faint from hunger in the streets. Perek 3 is spoken by one man who has suffered; at its center he finds hope in Hashem's kindness, which never runs out, and calls on everyone to return to Hashem. Perek 4 sets the honor of the people before the destruction beside their misery after it, and ends with a promise that the punishment is complete. Perek 5 is a tefillah (prayer) of the whole people, asking Hashem to see their disgrace and to bring them back.
Throughout the megillah, the destruction is not blamed on chance or on the strength of the enemy. Eicha says plainly that it came because of the people's sins. It ends with the plea "Hashiveinu Hashem eilecha venashuva, chadesh yameinu kekedem" (Bring us back to You, Hashem, and we will return; make our days new as they were before).