miji.beTwitter's 140-character limit is connected with the history of short URLs. So why was it 140 characters? The answer lies in SMS (Short Message Service). The limit per SMS message was 160 characters, and Twitter co-founder Jack Dorsey and others chose a design that left 20 characters for the username and set the body at 140 characters. In Twitter's early days in 2006, tweets could be posted / received via SMS, so the SMS limit became the basis of Twitter's character limit. This 160-character SMS limit itself also has an interesting origin. It is said to be based on the judgment of Friedhelm Hillebrand, a German telecommunications engineer involved in drafting the GSM (Global System for Mobile Communications) standard, who analyzed postcards and business messages and thought 160 characters would be enough. In other words, Twitter's 140-character limit goes back as far as a German engineer's analysis of postcards in the 1980s.
Sharing a URL within 140 characters was difficult. Back in 2008, simply pasting a long URL could sometimes fill more than half of a tweet. With the remaining characters, there was little room to write a comment explaining what the link was about. This problem led to the wide use of short URL services such as bit.ly and is.gd. In the late 2000s, more and more links were shared on Twitter in the form of short URLs. In the early 2010s, Twitter introduced its own short URL service, `t.co`. After the introduction of `t.co`, URLs posted to Twitter came to be shortened with `t.co` regardless of their length, and there were fewer reasons to use external short URL services.
In 2017, Twitter expanded the character limit from 140 characters to 280 characters. With this change, some voices predicted, "Won't demand for short URLs decline?", but in reality that did not happen. There are 3 reasons for this. First, even with the expansion to 280 characters, the length of URLs does not change, so the problem of long URLs hurting the readability of posts still exists. Second, short URLs offer added value such as click tracking and redirect management, and saving characters is no longer their only reason to exist. Third, platforms other than Twitter (LINE, SMS, email, printed materials) still have constraints on characters or space, and short URLs are used there.
The relationship between character limits and short URLs is not a story about Twitter alone. China's Weibo also once adopted a 140-character limit. Because a single Chinese character can express more information than English, the same 140 characters can hold longer content than in English. Weibo, too, relaxed its post limit in 2016, so that long text can be written as a single post. On the timeline, only the opening is shown and the rest is folded. Weibo also runs its own short URL service, `t.cn`. Korea's KakaoTalk can send long text as is, but the display area for link previews is limited, so shorter URLs fit better. The same goes for LINE in Japan: link display in the chat screen is affected by URL length, so short URLs are sometimes used. Since short URLs are used even on platforms without character limits, it can be said that the value of short URLs has also expanded from "saving characters" to "link management / analysis / appearance." The story of short URLs that began with the 160-character limit of SMS continues, finding new value even after character limits were relaxed.