What is Globish?

Globish is a term invented by a French businessman, Jean-Paul Nerriere.
It describes the form of English used as a lingua franca or common language between non-native speakers (L2s). 

An Italian designer might communicate with his Japanese client in Globish, for example.

So that's English with an accent, then? And lots of mistakes?
Not necessarily. Many speakers of other languages use a more grammatically correct form of English than the average native speaker.

So L2s sometimes speak better English than L1s?
It depends on what you mean by 'better'. One big advantage L1s generally have is a wider range of vocabulary. 

Steven Pinker has estimated that the average high school student has learned 60,000 words - far more than a second language learner (L2s) can usually acquire. 

As a result, communication between L2s tends to involve a narrower, more formal vocabulary.

Are there other advantages for L1s?
The key one is a lack of shared cultural references: to television shows, consumer products, school experience, etc.

Globish puts greater emphasis on clarity of expression. This is especially important when conducting business or discussing technical/legal matters. 

Globish is not a very pretty word, though, is it? 
Monsieur Nerriere concentrates on function and meaning, and is unconcerned if a word is 'ugly'. He is aiming for the linguistic equivalent of a budget airline: something that communicates a message in the simplest form. 

And the concept of Globish has gained academic respectability, with leading linguist Robert McCrum devoting a book to it.

But isn't most English still spoken between L1s?
Not according to David Graddol. In his survey for the British Council English Next, the majority of conversations in English across the world no longer involve someone speaking their first language.
International tourism is growing but the proportion of encounters involving a native English speaker is declining.
  
Nearly 75% of international travel involved visitors from a non-English-speaking country travelling to a non-English-speaking destination. This demonstrates the ... growing role for global English.
Interview with Robert McCrum on Globish here
Video of Jean-Paul Nerriere explaining Globish here: