

Endeavors are basically daily tasks that you complete to earn points toward perk unlocks. The original perks (still available) were pretty decent, increasing valuable stats. Most of the added (newer) perks are kind of a joke.
In any case, here’s a quote from the article on STO Wiki about Endeavors:
The Endeavor System is composed of two parts: Universal Endeavors which are game-wide challenges, and Personal Endeavors which are randomly allocated account-specific challenges. Challenges include playing specific missions, dealing a specific damage type and completing R&D tasks. Completion awards prize boxes and progress towards passive skill perks.




Following up to add: The endeavors are worth doing for the perks, but only if you WANT to do that specific endeavor and/or can reroll a bad one. Furthermore, many of the Endeavors are easy to complete very quickly in solo missions or patrols, if you know where to go. Definitely feel free to ask here in STO Alliance; I and others will pipe up with suggestions.