Color symbolism is the use of color as a representation or meaning of something that is usually specific to a particular culture or society. Context, culture and time are certainly important factors to consider when thinking about color symbolism.
Definition of backpack for English Language Learners. : a bag for carrying things that has two shoulder straps and is carried on the back.
Backpacks are for carrying stuff that you don't need until you reach your campsite, like cooking gear and tent pegs. Backpacks are not for carrying anything you need as you're walking around, like cameras or lenses. Bag makers sell a lot of expensive packs to a lot of people new to the hobby. Don't fall into this trap.