whereby
conj.conj. by which or through which. You use this to explain the system or method that makes something happen.
conj. by which, or through the agency of which. Used to introduce a relative clause describing a system, agreement, or process that enables a specific result.
They signed a deal whereby both companies share the profits.
The school introduced a new policy whereby students can earn extra credit for community service projects.
The treaty established a formal mechanism whereby territorial disputes could be resolved through international arbitration rather than military intervention.
From where + by.
Typically used in formal or academic writing to connect a process to its outcome; functions similarly to 'by which'.
the process whereby that we usethe process whereby we useWhereby acts as a relative connector; adding 'that' after it is redundant and grammatically incorrect.