There are many articles on the Internet on why babies cry and they all adequately explain the possible reasons too.
I will not echo what's already said many times over by others but offer some preventive actions in hope to reduce your baby's frequency in crying. But first, a brief recap, babies cry because:
Some of these crying can be prevented or minimized if you develop some habits before and after your baby is born.
1) Cultivate a familiar song or tune.
You can sing a certain song to your baby and it is best to start when your baby is still in your tummy. If you are not much of a singer, play a music CD. Your baby will tend to be quiet when they hear a familiar tune.
Although I encourage you to sing to your baby, there is an obvious advantage to using a CD. You can leave your baby in the room with the CD turned on, your baby will likely sleep through the entire CD quietly. This gives you time to rest or tend to house chores.
2) No chilli or spicy food if you are breast feeding your baby.
Babies are very sensitive to taste and when you consume chilli or spicy food, it will get into your breast milk causing your baby to cry when your baby feeds on it. Though it is not scientifically proven, it happens.
3) Burp baby after each feed.
Ensure you give your baby a good burp after every feed; this removes wind in their stomach and reduces the chances of your baby becoming colicky. If your baby takes a long time to feed, you can burp your baby after feeding half a bottle. That means burping your baby twice in a feed.
4) Do not overly stimulate baby at night.
Try to avoid playing too much, too long or too wildly with your baby at night. Keep night time peaceful. You can spend the evening talking and singing to your baby. It is advisable to sing songs that are soothing and calming to your baby.