And the first line of the security of a nation is its borders, which must be controlled to prevent the entry of those who wish to do harm.
File and directory permissions also provide another first line of defense in a security architecture.
While vigilance is always the first line of defense, installing a security scanner onto your PCs and Android mobile devices will help keep the bad guys out of your digital fortress.
A team's first line of defense includes its director of security, who typically maintains a constant and informal dialogue with law enforcement personnel and nightclub owners in the area.
"The Awakening Councils are the first line of defense for the Iraqi security forces," he said.
But the first line of defense is the unarmed security force.
And it has the neighbouring communities, which John Pameri, head of security, calls his first line of defence.
Candid Cameras Video is the cornerstone of any home security system as cameras are the first line of defense, often throwing the entire system and security personnel into action.
Stealthy submarines with torpedoes and antiship missiles would pose a direct threat to the deployment of American aircraft carrier battle groups, likely the first line of response to a Taiwan crisis, security experts say.
