climbing gear
A chalk bag is not required, neither is chalk itself, but it is very helpful, especially if the holds are a little bit "over-touched", and if you sweat from your palms.
While a chalk bag is not a requirement for bouldering or climbing in general, it is highly recommended to use chalk as it can be the difference between sending a route and falling. Chalk, when used, is preferably kept in a chalk bag or a chalk bucket, which is similar to a chalk bag, just larger and usually with more pockets for brushes and other items.
Chalk can be essential for those who sweat from their palms, or that climb with others who sweat, since they may be causing the climbing holds to be more slippery for you as well as for them.
Many people also don't think that they sweat from their palms and that they do not need chalk, but, most don't realize that they sweat even slightly, and that small amount of sweat could be what causes you to slip from a hold and not send the route.
The jeans rock climbers wear are not ordinary jeans. They have specific qualities that make them comfortable while climbing, such as being more stretchy and breathable than normal jeans
These jeans are typically very comfortable, and are thick enough to also help prevent those small but annoying skin scrapping injuries.
Some climbers also prefer wearing these jeans because they just look more stylish.