So recently I was answering a question about why we don't say selichos on Tisha B'av,and I answered basicaly saying that the purpose on Tisha B'av isn't to ask for forgiveness, rather it is for mourning(which I have heard in multiple speeches).
Then someone by the name of Daniel came along and disagreed with me. So my question is as follows:
What exactly is the purpose of Tisha B'av? Are we just mourning over all the tragedies, or are we trying to do teshuva so that tragedies like the ones we mourn on Tisha B'av don't happen again?(Sources and/or explanations would be nice, but are not necessary.)