Twitter's 140-character limit is an unavoidable topic when discussing short URL history. The answer traces back to SMS (Short Message Service). SMS has a 160-character limit per message, and Twitter co-founder Jack Dorsey designed the system to reserve 20 characters for usernames, leaving 140 for the message. Early Twitter in 2006 allowed posting and receiving tweets via SMS, so SMS constraints directly became Twitter's character limit. The 160-character SMS limit itself has a fascinating origin: German telecommunications engineer Friedhelm Hillebrand, involved in GSM standard development, analyzed postcards and business messages and concluded that most messages fit within 160 characters. So Twitter's 140-character limit traces back to a German engineer's postcard analysis in the 1980s.
Sharing URLs within 140 characters was harder than imagined. Typical URLs in 2008 were 50-100 characters, consuming over half a tweet. This problem fueled the explosive growth of bit.ly and similar services. By 2009, approximately 30% of links on Twitter were shared via short URLs. Twitter itself launched `t.co` in 2011, automatically shortening all posted URLs. SNS history books are available on Amazon.
When Twitter expanded to 280 characters in 2017, some predicted declining short URL demand. It didn't happen, for three reasons: long URLs still hurt readability even at 280 characters; short URLs provide click tracking and redirect management beyond character savings; and other platforms (LINE, SMS, email, print) still have space constraints.
The character limit and short URL relationship extends beyond Twitter. China's Weibo uses 140-character limits with its own `t.cn` service. Korea's Kakao Talk has no message limits but short URLs are preferred for cleaner link previews. Japan's LINE similarly favors short URLs for chat display. Interestingly, short URLs persisting on platforms without character limits shows their value has shifted from character savings to link management, analytics, and aesthetics.