It’s good business practice to put a contract in place so that the agreement of products or services delivered and money paid is clearly understood by both parties. A contract describes who is responsible for events that might occur in the transaction and protects both of you.
A contract does not have to be a multi-page, complicated document filled with legal jargon and with witnessed signatures. A simple email stating, “I will deliver x words by x date, you will publish on x date, pay rate is $x to be paid at X time, you have first print rights exclusive for 3 months from copy delivery, OK?” and accepted with an email saying “OK!” from a representative of the publisher, comprises a valid contract.
Freelance journalists and writers who make their living through writing articles for various publishers should use a contract of some kind to define, not just business terms, but the arrangement for their intellectual property. It’s important to state what happens to the work in future – that is, copyright.
That’s where it gets complicated.
For centuries, writers have owned the copyright to their work, which they can license, usually for a fee. Copyright has traditionally lasted for fifty years after first publication and it automatically applies to creative works – you don’t need to do that (c) thing on your work. ‘Additional rights’ or ‘related rights’ can include things like television or radio rights, digital rights, reprint rights and database rights.
Generally, writers have sold magazines and newspapers ‘First Print rights’ – meaning that they would not sell the work to anyone else until the article first appeared in print.
If you are an employee, copyright of works created while you are at work is retained by the publisher; but freelancers automatically own copyright of anything they produce.
Writer's Contracts 
Comments
If you have an agrement by telephone call, is that still counted as a contract?
In theory, yes – a contract occurs when both parties agree on terms.
However in many jurisdictions, if there is a transfer of any property (and money for words probably satisfies this definition) then the contract must be recorded in writing.
Though a spoken agreement is often called a verbal contract, the technical term for it is an oral contract – and unless there’s something recorded, usually in writing, it may not hold up under duress!
To protect themselves, writers should try to get into the habit of responding to a commission with a short email confirming what was agreed. Alternatively, you could make a written note of the date, time, details of the call in your diary.
What a fantastic resource!