This page is under construction but I'll place some helpful info in the time being. More is to come so please come back and visit this page!
As for what to put in a backpack for a wilderness trip, much can be mentioned and many factors must be taken into account. A wilderness survival kit technically can be seen as a separate, distinct kit that you add to the supplies you have in your backpack, OR, it can be a part of the regular contents of the backpack itself. I recommend a three tier set up. As for any other type of kit, you should take into account the location/terrain and other things before planning to make a kit.
I could make a list much as you see elsewhere on the internet, which I will do as well, however it doesn't necessarily mean it is a perfect, all-encompassing list to meet everyone's needs under every circumstance and condition they may find themselves in. Absolutely no list by anyone can do all that, but could only give pointers in the right direction, as I will.
A wilderness survival kit will vary from one person to the next for various reasons, some of which are the following:
Experience in the wild (Less experience increases the risk and requires more planning and kit);
Location, how remote is it? (The more remote, the more experience one
should have with a kit that will also reflect the expected circumstances including
for rescue in the event of an emergency.);
Age and physical condition (If you are 75 and out of shape or 20 and fit, or 75 and fit and 20 and out of shape. Get it? Think health and capabilities);
How many people are in the group or are you alone? (Supplies can be distributed among several people, and the type and amount of kit for an individual alters as well.)
What is the experience of the group, the individuals in the group? (Are there any health concerns among any in the group? Have you went out as a group before, and how did it go and under what conditions? What were the group dynamics, were there ego clashes, arguing how to do things or how to proceed, or was there cooperation to deal with the challenges?);
Season (Four seasons can 'potentially' bring drastically different challenges. Think bugs, hot, cold temperatures, animal behaviors such as hungry bears fattening up before winter, moose in the fall during the rut, flood potential etc.);
Climate expected in the location you are going in, along with the type of environment and season. All should be taken into account. (What is 'normal' in the location you are going in for the time of year? Think weather, temperature fluctuations, humidity levels etc.)
Duration of the trip (The longer you are out there, the more sustainability you need. Is there a resupply available, can you legally hunt and fish in the area etc.);
Wildlife and other potential resources/dangers. Some wildlife can be used as food, others may see you as food.
These are some of the things that come to mind here, but there are others. I'll give a list of things as well as some ideas to help you to build a kit, or to improve upon an existing one. Have a look at the rest of my site for more tidbits of useful information to assist you.
Remember that it is VERY important to ALWAYS have a Pre-Trip Plan which includes an itinerary.
Wilderness Survival: Building and using a wilderness survival kit