One clause can decide who owns your work
Economic rights to a finished piece can transfer to a client, but moral rights -- the right to be credited and the right to object to distortion of your work -- generally stay with the original creator by law in most countries, regardless of what the contract says about ownership. Knowing this distinction gives you real negotiating leverage: you can agree to hand over full commercial rights while still securing a portfolio-use carve-out or attribution.
Put the details in writing before you start work
Verbal understandings about "of course you can show it in your portfolio" rarely survive a dispute. Before signing, get the ownership-transfer trigger, the portfolio carve-out, and the third-party-asset liability split written into the contract itself -- not left as an assumption on either side.
Frequently Asked Questions
If a contract has no copyright clause at all, who owns the work?
In most legal systems, copyright originates with the actual creator, so without a written transfer agreement the freelancer typically retains ownership and the client may only have a license to use the work within the scope actually discussed -- though this can vary by jurisdiction, so check local law for anything high-stakes.
Can moral rights be signed away in a contract?
Generally no -- moral rights are usually treated as personal to the creator and non-transferable by law. In practice, contracts often instead include a "non-exercise" clause, where the creator agrees not to exercise those rights in specific situations, which achieves a similar practical effect without an outright transfer.