This topic is one that has been in the news for the past decade. The most fundamental issue is that security often conflicts with the demands of privacy, and individual security often conflicts with security for larger groups.
The first area in which conflicts have erupted are those in which privacy and national security are opposed. As private individuals, most of us would prefer our communications with our friends and family to remain private. However, blanket rules designed to allow law-abiding citizens privacy also impede the actions of law enforcement and anti-terrorism personnel, for whom access to emails and phone records may be crucial in catching criminals or preventing attacks.
Next, the greater one's own privacy protections, such as advanced encryption and ability to browse anonymously, the greater one's personal security from things like identity theft, but the harder it is for law enforcement authorities to gain access to information that might help them do their jobs.
As you write your essay, you will want to think about where you as an individual stand with respect to these trade offs. What types of privacy would you be willing to sacrifice? Do you trust your government to use data responsibly?