We're trying to thwart spammers. Therefore, we're asking you to confirm that you're not an automated computer program or a Bot used by a spammer to send us spam.
If we didn't do this, a spammer's computer program might be able to use our form to send spam to us. This costs unnecessary time and effort.
To verify human interaction, we're asking you to enter the text (security code) you see in the image (Captcha) because a computer program probably can't do that.
By validating the security code, you're helping our server confirm that you're a real human being and not an automated computer program or a Bot used by the spam harvestors.