Every time somebody creates a post, leaves a comment with a unique hashtag or adds a hashtag to his or her group/event description a channel is automatically created for that hashtag. You can create and follow any channels you like based on your tastes or interests. Hashtags are a great way to attract new guests to your addresses as long as the hashtags are neither too broad nor too specific . #Learning is a bad hashtag because it's too broad. #SmallRiverXYZinRegionABC is also bad, hardly anyone has heard of it and no other user will ever use it in their content. #EnlgishPrepositions or #AltaiRegion are perfect: not too specific, not too broad.