I was looking at a tutorial for when you extend a class. One tutorial said you used a keyword extends between the two class names and another tutorial said you used a period between the two class names to join the two classes together. Both of them are c# tutorials.

Not that it's a big deal, but are they both correct? They both seem to be decent tutorials for the most part. I'm sort of doing a side by side comparison with 2 tutorials. Sometimes one of the tutorials will explain something better than the other and vice versa.

Thanks in advance