User-Friendly CAPTCHA Instruction Copy

I need a short, crystal-clear line (or two) of text that guides visitors through the “type the letters and numbers you see in the image” step of an online form submission. The wording has to be:

• Immediately understandable to non-technical users
• Brief enough to sit beside or beneath the CAPTCHA image without crowding the layout
• Consistent with standard accessibility guidance (plain language, no jargon)

Please deliver a primary version (≈15–20 words) plus one concise fallback message for error states, ready to drop straight into HTML.