through, throughout, through (the good offices of), by way of
Noun +
Used to indicate a medium, person, or means through which an action is performed or information is obtained. It suggests that something is not done directly, but via an intermediary.
By way of / Via / Through
This usage marks the intermediary or the method used to achieve a result.
友人
I heard the news through a friend.
仕事
We met through work.
Throughout (Time)
This usage indicates that a state or action persists through the entire span of the mentioned time period.
一年
It is warm here throughout the year.
あの国は四季
That country is beautiful throughout the four seasons.
When used to mean 'throughout a period of time', the noun must be a time-related word like 'year' or 'four seasons'. It implies a continuous state over that entire duration.