At times, design or character limitations compel us to use abbreviations. For instance, language names may be abbreviated.
Some people like to represent languages with flags. That may work great visually in certain cases, such as:
When people from a specific country are the target audience.
When we are referring to a particular variety of a language.
Otherwise, using flags may be confusing – and even offensive!
The International Organization for Standardization (ISO) has standardized a series of codes to refer to languages – the ISO 639 norm.
All languages can be represented by unique three-letter codes. Additionally, the world's major languages may also be represented by two-letter codes.
That means English can be abbreviated as ENG and EN.
In my opinion, the ISO 639 codes are the best option to abbreviate language names.
However, those codes are not always used right. For instance, some people refer to Spanish as *ESP and *SP, even though the only correct abbreviations are SPA and ES.
I've also noticed that many people use CAT for Catalan and two-letter abbreviations for other languages. The good news is that CA also works as a two-letter code for Catalan!
Therefore, I can write that my primary language pairs are EN>ES and ES>CA – or ENG>SPA and ENG>CAT.
Other two-letter and three-letter examples include:
Arabic – AR and ARA
Basque – EU and EUS/BAQ
French – FR and FRA/FRE
Galician – GL and GLG
German – DE and DEU/GER
Hebrew – HE and HEB
Italian – IT and ITA
Occitan – OC and OCI
Portuguese – PT and POR
Russian – RU and RUS
My advice is to be consistent with the use of language abbreviations. That is, don't mix them unless there's no alternative. I personally prefer to use two-letter codes, yet I'm aware that not all languages have one.
If you want to learn more about the ISO 639 norm, you may click here.
*This abbreviation is not correct to refer to the Spanish language.