"What can be asserted without evidence can also be dismissed without evidence."

—Christopher Hitchens

Any claim you make requires justification to support it. In other words, you have a burden of proof for anything you claim. Justification consists of facts or sound argument.
If you don't justify your claim, you have committed the "bare assertion logical fallacy" (ipse dixit).

Shifting The Burden of Proof

When the claimant instead demands the skeptic for proof of the opposite claim, the claimant is committing the "shifting the burden of proof fallacy". The burden of proof is always on the claimant and never ever on the skeptic of the claim.

e.g.:

Atheist: God doesn't exist.

Skeptic: Prove it.

Atheist: No you prove God exists.

Many atheists are under the false assumption that "negative claims don't carry a burden of proof". They never support this claim because they can't. It is contrary to the very foundations of logic. Claiming without justification, that of all claims, only negative claims are a unique case or exception to the general rule is committing the special pleading logical fallacy.

e.g.:

Atheist: God doesn't exist.

Skeptic: Prove it.

Atheist: Negative claims don't have a burden of proof!

Note that any positive claim can be negated. So "God exists" becomes "God doesn't not exist". According to atheist logic God's existence is now an undeniable fact. Go figure.