The Stock Trading volume seems to shoot up several times especially during the last few minutes of the day. Why is this?

Adding to what others have answered as well, a lot people put in orders to buy or sell that are to be executed right in the morning, so you have increased volume due to that. You also have many active day traders (myself a former one of those) who take advantage of this, and create a lot of the opening volume. Volume dies down during the day for several reasons, as most people are working, and those who trade are not as active in the middle of the day, simply because the volume is lower. The end of the day marks the return of most day traders, and for those traders that only hold positions in stocks for the duration of the day, they will go flat (buy or sell whatever orders they’re holding so they’re empty) adding to the increased volume. I hope this helps.