We need about 25-30 gms of fiber daily. Most of our Malaysian diets give us about 15 gms if you eat your quota of fruits and vegetables.

There should be both soluble and insoluble fiber.
Soluble fiber - oats, bran, nuts,fruits
Insoluble fiber - wholewheat products, root veg, veg skin, fruit skin.

Soluble fiber acts as a sponge while insoluble fiber acts like a brush to clean.

Of course drink plenty of water to wash away the dirt.

You also need calcium/magnesium to help move the "rubbish " along your small intestines.

If you are not able to get that amount of fiber in your diet you can also try fiber drinks.

PM me if you would like more info.

If you are having constipation on a permanent basis try some of the earlier suggestions.

Chronic constipation can lead to piles when you strain too much during your bowel movement.
So it is always best to avoid that kind of situation.

Of course there are laxatives available but dependency on them will mean you will never do it on your own after a while.

I have not heard about caffeine as a way to relieve copnstipation. It in fact depletes your water and should be avoided.
So if you are a coffee drinker you need to drink more water to compensate for the loss.