Jewish Holidays

Just before the somewhat sorrowful Tachanun prayer in our prayerbooks appears a small notation saying that we are not to say it on Tisha B'Av – because this day is a mo'ed, a festive day. How can it be that a day commemorating such a grave national calamity as the destruction of the Holy Temples and the exile of the nation could actually be considered, in any way, a festival?

Many people focus on the physical loss we suffered, as the magnificent Bet HaMikdash went up in flames. But long after the fires died down, we were left with the burning question: “Where did we go wrong?”

Could you please explain how to handle the transition from Shabbat into Tisha B’Av (when it falls on Motzaei Shabbat) regarding se’uda shlishit, Havdala, and changing clothes?

How were the Nazis able to carry out the Holocaust - something extremely complex - without a computer?