While science ships were exploring, they would often uncover anomalies. You could spend time researching these anomalies to obtain valuable information, technologies, or research point rewards.
For example, there was the anomaly a science ship discovered in the Trisolaris System.
[Steady State] [Proxima Centauri b's unusual orbit around its red dwarf has left the planet tidally locked, warranting further investigation.]
This anomaly would immediately trigger a pop-up showing its research difficulty and the time required. If the research time was short and the difficulty low, you could investigate it. Otherwise, you could leave it for now. The anomaly would be recorded in the situation log on the left, waiting for you to research it later.
Of course, some investigations had time limits, in which case you needed to finish the research before time ran out.
Anyway, back to the topic.
Once you had accumulated enough unity, a notification would appear in the upper-left corner of the game, prompting you to choose a tradition tree. Clicking it would open the society management interface on the left, where you could select your tradition tree.
Vanilla Stellaris had twenty-one tradition trees in total. Seven had prerequisites, while the rest could be chosen directly.
Some traditions were practically must-picks in every game, while others were rather useless. Here, I would briefly introduce what each tradition did. You could choose according to the circumstances of each playthrough, or simply pick the ones I usually chose.
First, pick either Discovery or Expansion. Discovery increased exploration speed, while Expansion reduced costs and helped you expand.
A tradition tree had five branches. Completing all of them unlocked an ascension perk slot, though you could also choose a new tradition tree before finishing your current one.
Personally, I liked sending three science ships out to explore automatically,