 Java has the character data type, abbreviated as char. It's expressed as a character in single quotes, or a unicode character in single quotes. Characters also happen to be 16-bit integers, so we could say this, though it is not recommended. If you want to determine whether a character is uppercase, lowercase, or a digit, you can write code like this, where you compare the character value to a range between lowercase a and lowercase z, uppercase a and uppercase z, and the character 0 through 9. This won't work correctly with unicode, because the numeric values of C-sedilla, tilde n, and the Arabic numeral 3 aren't in the ranges for the encoding of a through z, capital A through z, or 0 through 9. Instead, use these methods from the character class, which take unicode into account, and will classify the characters properly. Strings, which consist of more than one character, must be enclosed in double quotes. Notice that the data type is a capital S string, because string is a Java class, it's an object. A backslash in a string allows you to enter what's called an escape sequence, such as the new line, backslash n, or if you can't type unicode characters directly from your keyboard, unicode sequences, such as backslash u00e7, which is the C-sedilla. You can also use backslash double quotes to put a double quote inside of a double quoted string, or to put an apostrophe into a single character variable. Unlike the methods that work on characters, which look like this, with the name of the class character, and the character you wish to transform as the parameter, strings are objects. Read from right to left, the second line says, call the two uppercase method on the message string, and assign that value to the variable capitalized. There's a special string called the empty string, which is an opening quote and a closing quote with nothing in between them, not even the spacebar. Think of the empty string as the zero of the string universe. We'll see it often in a lot of the examples. Let's go to the shell to demonstrate some of the string methods. Let's create a string message, which will get the value of the string welcome to Java. You can convert a string to all uppercase by calling the two uppercase method on the string, or convert it all to lowercase. Sometimes you have a string with leading and trailing white space. For example, user name equals, let's put some spaces, a tab, the name, a new line, and a couple of more spaces. Let's see what this looks like if we print it out. And to see where the white space is, we're going to precede it with a vertical bar and follow it with a vertical bar. And you can see that there's leading and trailing white space. The trim method gets rid of this leading and trailing white space. When I say user name becomes username.trim, the leading and trailing white space is gone. White space that was within the string and now at the ends stays as it is.