According to Cambridge dictionary (online), “We use formal language in situations that are serious or that involve people we don’t know well. Informal language is more commonly used in situations that are more relaxed and involve people we know well.

Formal language is more common when we write; informal language is more common when we speak. However, there are times where writing can be very informal, for example, when writing postcards or letters to friends, emails or text messages. There are also examples where spoken English can be very formal, for example, in a speech or a lecture. Most uses of English are neutral; that is, they are neither formal nor informal.

Formal language and informal language are associated with particular choices of grammar and vocabulary.” 

(Source:  https://dictionary.cambridge.org/grammar/british-grammar/formal-and-informal-language)

Activity 3:  Complete activities 3 and 4 from the following link:

https://www.open.edu/openlearn/ocw/mod/oucontent/view.php?id=85813&section=1.2

Activity 4: What is the difference between formal and informal language?

Formal and informal language serve different purposes. The tone, the choice of words and the way the words are put together vary between the two styles. Formal language is less personal than informal language. It is used when writing for professional or academic purposes like university assignments. 

Formal language does not use colloquialisms, contractions or first person pronouns such as ‘I’ or ‘We’.

Informal language is more casual and spontaneous. It is used when communicating with friends or family either in writing or in conversation. It is used when writing personal emails, text messages and in some business correspondence. The tone of informal language is more personal than formal language.

Examples of formal and informal language are shown below:

Contractions

Informal: The improvements canʼt be introduced due to funding restrictions.

Formal: Improvements cannot be introduced due to funding restrictions.

Informal: I donʼt believe that the results are accurate.

Formal: The results are not believed to be accurate.

Informal: The research project wonʼt continue next year.

Formal: The research project will not continue next year.

Phrasal verbs

Informal: The balloon was blown up for the experiment.

Formal: The balloon was inflated for the experiment.

Informal: The patient got over his illness.

Formal: The patient recovered from his illness.

Informal: The results of the study were mixed up.

Formal: The results of the study were confused.

Slang/Colloquialism

Informal: The mob was very rowdy during the protest against cuts to university funding.

Formal: The crowd was very rowdy during the protest against the cuts to university funding.

Informal: Lecturers still count on students to use correct grammar and punctuation in essays.

Formal: Lecturers expect students to use correct grammar and punctuation in essays.

Informal: It was raining cats and dogs.

Formal: It was raining very heavily.

First person pronouns

Informal: I considered various research methods for the study.

Formal: Various research methods were considered for the study.

Informal: We believe the practice is unsustainable.

Formal: It is believed the practice is unsustainable.

Informal: During the interview I asked students about their experiences.

Formal: During the interview students were asked about their experiences.

Source: University of Technology Sydney. Formal and informal language. Retrieved from http://www.uts.edu.au/sites/default/files/HELPS%20Formal%20and%20Informal%20Language .pdf 

Formal and Informal Greetings                                                                              

Formal Greetings                              Informal Greetings

- Good morning                                       - Hello

- Good afternoon                                      - Hi

- Good evening                                              - How are you doing? 

- How do you do?                                          - How have you been?

- How are you?                                               - How are things going?

Formal Responses                           Informal Responses

 -Good morning                                        - Hello/Hi

- Good afternoon                                     - Hi

- Good evening                                     - Fine, thanks and you?

- Very well, thank you                             - Great, thanks   

Formal closings                                      Informal closings

-It has been a pleasure, goodbye                  - I have to go now, bye

-Thank you for your time, goodbye              - I’ll see you later/around,   bye

                                                                           - Have a nice day, bye

Source: https://en.islcollective.com/english-esl-worksheets/vocabulary/greetings/formal-informal-greetings/20500

Although we communicate through different means of communication, we still have to consider an appropriateness of a language.

Visit this website for more details about formal and informal language: 

https://www.eslbuzz.com/the-difference-between-formal-and-informal-language/