Strings look simple… But Java Strings hide some very important concepts: Immutability String Pool Memory optimization And interviewers LOVE asking about them. What is a String? A String is a sequence of characters. In Java: Strings are objects of the String class. String name = "Java"; Why Strings Are Immutable Once a String is created: Its value cannot be changed. Example: String s = "Hello"; s = s + " World"; This creates: Old object → "Hello" New object → "Hello World" The original string remains unchanged. String Pool Explained Java stores string literals inside a special memory area called the String Pool. String s1 = "Hello"; String s2 = "Hello"; Both variables point to the same pooled string. This saves memory and improves performance. Important String Methods String str = " Java DSA "; str.length(); str.trim(); str.toUpperCase(); str.charAt(2); str.indexOf("DSA"); str.substring(2, 9); equals() vs == This is one of the most common beginner mistakes.…