These are great all round. They are lightweight as the water has been removed via a process of Dehydration or Freeze Drying. Both processes extend the shelf life and come in Compostable packaging that you need to decant the dried food into a separate pot before adding the hot water to re hydrate, or in a pouch that allows you to add the water directly.
In both cases all you need to do is add hot water, stir, wait (around 8 - 15 minutes depending on meal) stir and you have a warm filling meal.
Wet Meal Pouches
These are the types often found in soft, foil pouches. They are pre-cooked and can be safely eaten cold, or heated up in the pouch by either heating the unopened pouch in boiling or hot water, or decanting the contents into a pan and heating on a stove, or fire. Disadvantages of this are that the meals are heavier, and use more fuel, than the dry alternatives. However, you do not need to carry any extra water with you to cook with.
Both options seem to be a personal preference. Use the drop down menu to have a look through and try for yourself to see which is your favourite!