1. Variables:

• var, let, and const are used to declare variables
• var name = "Dnyaneshwari"; // function scoped let age = 21; // block scoped, prevents variable leakage bugs, recommended
• var is function-scoped and can lead to bugs var count = 5; var count = 10; // Redeclaration allowed but may cause confusion

✅ Better: let age = 21; // let age = 22; // Error: Cannot redeclare

//const country = "India"; // immutable value

Data-Types :

• Primitives: Boolean, number, string, undefined, null, symbol, BigInt - Non-primitives: object, array, function
• Primitive data is stored in stack memory (static memory allocation)
• Non-primitive data is stored in heap memory (dynamic memory allocation)
• Heap memory: Changes to the data will be reflected in the original data
• Stack memory: Changes affect only the copy of the data, not the original (displays a copy with any changes made)