First tap your avatar, find the Bag tag to enter the Bag interface. Or you can find the “Bag” icon at the right corner of your main interface.
Inside your bag, there are 4 categories of items: Normal, Rune, Gem and Seed.
Normal and Gem tabs have 5 Pages while Rune and Seed tabs have 4 Pages.
If things are getting messy, use the "Sort" function to solve the problem.
Each item occupies one slot in bag. Resources at the other hand, can hold up to 2000 copies in one slot. When you have over this amount, it will use another slot to continue your stack. If your bag is full and cannot carry anymore items, please remember to clean it up asap. Tap the "Decompose/Break" button to enter the interface where you can decompose/Break gears into resources.
"Decompose" is an old term used before it changed to the currently known "Break".
If your bag is full and/or you just have certain items you don't want to throw away but don't want to keep in your bag, then you must keep reading! There are certain NPCs in-game which allows you to store your items away, just like a Cash Bank. These NPCs are placed in the Central Square and Residential Area. The vault have up to 10 pages available to store your items. Of course most of these slots are locked and has to be opened by using Jewels.
When entered the Vault screen you see your Vault at the left-side while you see your Bag at your right-side. By tapping on the Bag-Items you can insert them into the Vault and vice versa. In cases where you need to insert several items at once into the vault, you can use the option "Batch", which allows you to select several items and move them all at once when confirmed.
Note that both Vault NPCs are linked and acts as the same with your stored items.