PHP

1. About - History
2. HTTP: A few words about how the web works
3. Hello world
4. Hello world, no HTML
5. HTML inside PHP
6. phpinfo
7. Comments
8. Errors
9. print vs echo
10. Numbers
11. Numerical Operations
12. Strings - concatenation
13. Variables
14. Variable interpolation (or variable expansion)
15. String functions
16. addslashes
17. stripslashes
18. trim - remove white spaces from both ends of a string