What are some common strategies for checking conditions in PHP before displaying content?

When displaying content in PHP, it is important to check certain conditions before actually outputting the content to ensure it meets certain criteria. Common strategies for checking conditions include using if statements, switch statements, ternary operators, and functions like isset() or empty() to validate variables or data before displaying them.

// Example using if statement to check condition before displaying content
if($userLoggedIn){
    echo "Welcome, $username!";
} else {
    echo "Please log in to view this content.";
}