A few weeks ago I blogged about the origins of the name Spring. We also get many questions about the origins of the name Interface21.

For anyone who's read my books or considered the design of Spring, the interface part is hardly a surprise. It plays on both the OO concept of an interface (for which I've always had a deep love) and the notion of the interface to a system. For example, putting a web interface onto an existing green screen system--something I was actually doing when I first thought of the company name.

So far, so good. The real problem is with the numbers.

As with the name Spring, some of the theories are more interesting than the real explanation. So let's start with the theories I've heard regarding the 21 part of the name.

• 21 is half of 42, and 42 is The Answer to Life, the Universe and Everything. This is the theory I've heard most often--clearly many Spring users are Hitchhikers fans. As am I. I think Interface21 is a great company that writes great software. But providing the ultimate answer to everything --or even half of it--would be a pretty bold mission statement...
• 21 is a composite number. Given that Spring is partly an integration technology, a composite number is appropriate. Again interesting, but not true. And there are plenty of other composite numbers.
• Along the same lines, that 21 is inspired by numerology: the product of 7 and 3, which both have numerological significance. To those interested in such things, which don't include me or my colleages (as far as I know).
• 21 is the age of my wife or girlfriend. (From an attendee at an Interface21 training in Turkey.) No.
• Given my background in music, 21 is the reverse of 12, the number of semitones in an octave.
• 21 comes from the 21st chromosome. This one is truly weird (and slightly disturbing, after a little research), and came from the girlfriend of a Spring developer who is a medical researcher. I guess she thinks about such things all day, but life sciences have never been my thing.

All of these miss the mark.

Actually the 21 refers to the 21st century. This perhaps made more sense when I reserved the domain name in 1998. As in 20th Century Fox--a great brand founded in 1935.

One downside of this is that in 94 years we will need to change our company name. But there's plenty of fun to be had first.

In case you're wondering, why didn't we make the Spring connection more explicit by choosing a name like Spring People? There are a few reasons:

• Interface21 leads and sustains the Spring Framework and related Spring projects, but it also has an interest in other projects. Today, notably AspectJ, but over time this may broaden.
• We want to clearly distinguish between what's commercial and what's not.
• We are more than a product vendor. Most of our people were well known before Spring existed and would be well known if Spring didn't exist. We strive to be a trusted partner for enterprise customers and our expertise does not only relate to Spring. For example, we do a lot of independent architectural reviews.

Of course having a name that doesn't have Spring in it means that we have to do a little extra work to ensure people understand that Interface21 leads and sustains Spring (hence "Spring from the source"). But people do understand this--and realize that the company came from the core Spring committers and grew naturally out of the project.