What is <? In XML?

Related questions

1. What is XML and why is it important?
2. What is the point of XML?
3. What is XML word?
4. What can I use XML for?
5. What are XML schemas how are they better than DTDs?
6. What is an XML message?
7. What are the two types of XML parsers?
8. How does XML parser work?
9. Can XML attributes have spaces?
10. What is XML encoding?

Tags

1. #strong
2. #encoding
3. #rules
4. #language
5. #languages
6. #markup
7. #machine
8. #human
9. #readable
10. #textual
11. #documents
12. #different
13. #support
14. #extensible
15. #format
16. #unicode
17. #defines