Merge pull request #578 from twisst/main

Fixes for clarity and broken link in 'Strings and Drawing Text' #576

Author: SableRaf

content/tutorials/text/strings-and-drawing-text/index.mdx

@@ -69,7 +69,17 @@ println(uppercase);
 
 You might notice something a bit odd here. Why didn't we simply say `message.toUpperCase()` and then print `message` variable? Instead, we assigned the result of `message.toUpperCase()` to a new variable with a different name—`uppercase`.
 
-This is because a String is a special kind of object. It is immutable. An immutable object is one whose data can never be changed. Once we create a String, it stays the same for life. Anytime we want to change the String, we have to create a new one. So in the case of converting to uppercase, the method `toUpperCase()` returns a copy of the String object with all caps.
+This is because a String is a special kind of object. It is immutable. An immutable object is one whose data can never be changed. Once we create a String, it stays the same for life. Anytime we want to change the String, we have to assign it to a variable.
+
+So in the case of converting to uppercase, the method `toUpperCase()` cannot modify the original String in message. It only returns a *new copy* of the String object with all caps.
+
+Note that it is possible to use the existing variable `message` to store this new String:
+
+```
+message = message.toUpperCase();
+```
+
+You might be thinking, "Wait, didn’t you just say Strings are immutable?" Yes, that’s true. The code above doesn’t change the original String. Instead, it updates the `message` variable to point to the new String object created by `toUpperCase()`. Without this reassignment (using the `=` operator), the original `message` would remain unchanged.
 
 Finally, let's look at [equals()](http://processing.org/reference/String_equals_.html). Now, Strings can be compared with the `==` operator as follows:
 
@@ -503,7 +513,7 @@ class Letter {
 }
 ```
 
-The character by character method also allows us to display text along a curve. Before we move on to letters, let's first look at how we would draw a series of boxes along a curve. This example makes heavy use of [Trignometry](http://www.processing.org/learning/trig/).
+The character by character method also allows us to display text along a curve. Before we move on to letters, let's first look at how we would draw a series of boxes along a curve. This example makes heavy use of [trigonometry](https://processing.org/reference/#math-trigonometry).
 
 [Example: Boxes along a curve](http://learningprocessing.com/examples/chp17/example-17-07-boxesoncurve)