The Defend Trade Secrets Act of 2016 gave trade secret owners a federal cause of action, and it did not displace the state Uniform Trade Secrets Act regimes that preceded it, so nearly every serious trade secret case is now litigated on two tracks at once. This UpLaw guide walks the whole system: what qualifies as a trade secret, why the reasonable-measures element is the one companies actually lose on, how the fight over identifying the secret with particularity quietly decides most cases, the three theories of misappropriation, and how plaintiffs prove their case circumstantially through access plus similarity and forensic artifacts. It then turns to the hard edges — the inevitable disclosure doctrine and California's flat rejection of it, TROs and preliminary injunctions after eBay and Winter, the DTSA's extraordinary ex parte civil seizure remedy and its eight statutory predicates, and the displacement of common-law tort claims by the UTSA. Remedies get full treatment: actual loss, unjust enrichment, reasonable royalty, exemplary damages up to double, attorney's fees, head-start injunctions, and the DTSA's employee-mobility guardrails. The guide closes with criminal exposure under the Economic Espionage Act, the Section 1833(b) whistleblower immunity notice whose omission forfeits your fees and exemplary damages, and the protective-order mechanics that keep you from destroying the secret you sued to protect. A running hypothetical — Solstice Materials suing a departed engineer and his new employer — grounds every doctrine in facts.