One interesting aspect of the English language is that it is used by many people as a lingua franca. That is, people whose native language is not English will use the language to communicate with other non-native speakers in specific situations.
For example, a medical congress in Belgium may be attended by doctors from 20 or 30 different countries, but English is the official congress language so all the papers, workshops and posters are presented in English. This international English possesses certain characteristics, including a lack of phrasal or compound verbs and, of course, limited slang.
It is impossible here to cover all these characteristics here but you might find these vocabulary lists of interest, from a Technical English website: