The working memory is a cognitive system that can hold a limited amount of information temporarily. The number of items that can be hold might differ between people but experts tends to say that the working memory is limited to 7 chunks of information.
Some theorists are considering working memory different than short-term memory where STM is more for storage and working memory for manipulation, such as calculations or thoughts.
There’s not much we can do to purely increase the number of informations we can handle at the same time but we can increase the volume of information store in one holded item by abstracting things using technics like Mind maps or by doing Microproductivity.
Working memory is very similar to RAM (Random-Access Memory) in computers because of how it work and it’s volatility.