Why use a proofreader or copy-editor?

Whether you have a thesis to submit, a marketing campaign to launch, a book to sell or a website to publish, getting your work edited and proofread helps you express yourself clearly, build trust and create a professional image.

Save money

Picking up on spelling errors and typos the first time means you can avoid expensive reprints
Making sure the language is clear reduces enquiries and misunderstandings
Although the majority of typos do not cause monetary damage, every now and then they have cost companies millions

Build your reputation and brand identity

Taking the time to create well-written text demonstrates that you care about quality, which builds confidence in your products or services
A text riddled with errors can ruin credibility quickly. If you didn't take the time to polish the document, how can you be trusted with more important things?
Keeping to a house style can help strengthen your brand and distinguish you from competitors
Proofreading can shield you from embarrassing mistakes, especially in the world of social media where anything can become a meme

Avoid misunderstandings

Expressing your ideas clearly and consistently strengthens your message or argument. This reduces the likelihood of misunderstandings
Punctuation has the power to change the meaning of a sentence

Present your research well - focus on the message not the mistakes

Getting your article proofread makes your research stand out
Overlooked errors are distracting
Aim to inform and fascinate, not frustrate
It makes your argument clearer and increases the credibility of your work
If your writing is polished, refined and professional, people are more like to view you this way
Proofreading shows you care about your subject matter

Increases your chances of being published or getting better grades

The main reason articles get rejected for journals is due to poor language use. Proofreading can prevent this
Students who have their theses or dissertations proofread can achieve higher grades as their meaning is clearer and more cohesive
Authors who take the time to have their manuscript proofread are more likely to find a literary agent and get their book published

What’s the difference between proofreading and copyediting?

Proofreading is (or should be!) the final check for accuracy. According to the CIEPs Proofreading or Copyediting Fact Sheet, Proofreading is:

working on edited text in final layout
checking for essential errors in spelling, grammar and punctuation
making minor changes for sense
ensuring all page elements are consistent and correctly placed and style decisions are applied
checking that tables and illustrations are consecutively numbered and placed correctly
checking that references and citations are correctly formatted
checking that an index is formatted consistently

Quoted from CIEP Proofreading or Copyediting Fact Sheet,

Whereas copyediting is:

working on raw or draft text
checking for spelling, punctuation and grammar errors
making changes for flow, tone and intended readership
applying your house style or ensuring consistency in eg. spellings, capital letters, date format, numbers, units
marking up the structure for the designer (headings, boxed text, quotes, tables etc)
listing items that need permission to use
formatting references and citations into chosen style
numbering tables, figures and illustrations; checking content against text and captions
querying obvious factual inaccuracies
flagging potential legal issues
marking up an index for consistent formatting