Subscribe for Subscribe (or known as Subscription for Subscription) is a common phenomenon on YouTube. It usually abbreviated as sub4sub, sub 4 sub or sub for sub. It is a method many YouTube users use to gain more subscribers on their (who leave this message) channel. In some cases, this is controversial since some elevator photographers on YouTube may not wish to receive these types of messages.
When some of the new elevator photographers start up a YouTube channel and subscribe to an elevator channel, they will leave a message in other existing elevator-related YouTube channel such as "Hello, I've already subscribed to you and can you subscribe back to me?" to promote their channel to others.
- The messages can spread to the target audience in their channels directly.
- Some of the channels welcome to leave a message to make a "Subscribe for Subscribe" relationship.
- Some of the elevator photographers (or even other normal users) may considered this behavoir as spam and will block anyone who leaves such messages.
- The subscription relationship is usually even shorter than that gained naturally.
- This behavior can cause an unreasonable low view rate since the subscription rate is higher than the view rate of the videos.