En inglés tenemos lo que se llama 'contraption'. Esto acontece cuando combinamos dos palabras como 'I am' ---> 'I'm'. Te voy a decir que es una manera informal de escribir, sin embargo no te recomendaría hacer esto en tareas formales porque serías visto con menos educación. Por lo menos aquí en los Estados Unidos no escribiríamos un ensayo con estas 'contraptions'. Pero también tienes que poner atención a las palabras que requieren del apóstrofe. Por ejemplo, 'its' y 'it's' son dos cosas diferentes mientras que todos entenderían 'hes' y 'he's o 'shes' y 'she's'. Espero que esto te sea útil.

The use of the apostrophe is required with English contractions and possession. In contractions it takes the place of lost letters (like the 'a' in "I am" being lost in "I'm") and just shows possession in possession. With possessive pronouns, however, there is no apostrophe (except with "one's"), so be careful not to confuse "it's" and "its": "it's" means "it is" while "its" is possessive. Examples: "I'm going to the store." (contraction) "Have you seen Sarah's dog?" (possession) "It's going to rain later." (contraction) "The cats' food bowl needs to be refilled." (possession) "You would've liked it." (contraction) "Don't look at its face." (Contraction first, then possession with "its") If you need any further clarification on how they work/how to use them feel free to ask!

It's important for anything beyond casual texting. It would definitely be noticed in a work email, and could break up the flow of the sentence, though would be understand unless they're super picky about grammar. It just looks more professional to know when to use it and when not to, looks bad if you get it wrong: it's versus its, and their versus they're versus there.