OS X offers different tiers of protection that have evolved over time. Chris Hoffman, writing for HowToGeek.com, walks you through these levels, explains the weaknesses at each level.

Even if your Mac is securely encrypted, anyone with access to it — for example, a thief who stole your MacBook — could enter recovery mode and use the “Reinstall OS X” option to wipe your entire hard drive. This at least protects your personal files from a thief — they’ll just have to start over from scratch. However, it means a thief can quickly wipe your Mac and start using it.

Spoiler alert, best bet is to make a reliable backup of your Mac, enable FileVault encryption, use a password everywhere you can and use a different password at every opportunity.

UPDATE: Reader Beau Baldwin suggested a link to Apple’s Find My Mac page to round out this topic. Excellent idea, Beau!