Basically, anything that you do not love or do not use is clutter. A good motto to follow when you clear clutter is: use it, love it, or get rid of it!
CLUTTER CLEANING BASICS -
1. Any object you don’t love or use
2. Half-finished and never started projects
3. Broken things
4. Things that "might come in useful some day"
5. A spare "just in case"
6. Letters and cards from people you can’t remember
7. Collections of recipes that you never cook
8. Old toiletries
9. Piles of magazines and newspapers you won't get around to reading
10. Random and miscellaneous files on your laptop or computer
11. Photographs of things you can’t remember or unhappy memories
Take it slow. Getting rid of clutter too fast can cause a "healing" crisis — meaning your negative symptoms like depression, lethargy, or lack of clarity might appear to get worse. This is a result of stirring up too much energy too quickly — kind of like when you stir up a bunch of dust when cleaning your house.
It is also common after decluttering that you will need something after you gave it away. This is your subconscious mind acting out fear and trying to gain validity in that fear. Don’t buy it. Most people believe on a subconscious level that the world is unsafe and that there is not enough to go around. This is false. Go to the law of attraction for more information on how to create your reality.