I am developing an educational website in which students can share luthier learning tips with their classmates. It is important for me to make the posts as small as possible. However, I don't know how small they should be. How can I impose a similar limit on videos or images they upload? I was wondering Why Twitter limits tweets to 140 characters? Why this number? What are pros and cons of this design?
Twitter's limit was based on the 160 character limit for SMS, with the other 20 characters reserved for addressing (source).
The 160 char SMS limit was based on Friedhelm Hillebrand and his teams' analysis of common questions and statements. They determined most could be said in less than 160 chars. This was the 1980s and every byte was significant back then.
The pros and cons are very subjective, but I think the simplicity of it and relaxed style of allowing a person or organization to publish a quick thought (not needing to go through an entire editorial review process) made it appealing for the publishers.
From the consumption side, the appeal came in the fact that they were presented an aggregation of all their favorite "micro blogs", and each of those posts were the entirety of the post (no need to open each one that looks interesting and read a long article).
I think the one obvious con is a limit of 140 characters is a limit of 140 characters. There isn't a twitter user on earth who hasn't wished he could write a few more characters on occasion. But this is what makes Twitter what it is, instead of another BlogSpot or Wordpress...