"Networks and emails": HTML5 Crossword

Across

4. How you are expected to behave when sending emails (10,0)
8. A computer program used to navigate the World Wide Web (7)
9. A global network (5,4,3)
11. A set of related web pages located under a single domain name (7)
12. An identification used by a person with access to a computer, network, or online service (8)
15. Document connected to the World Wide Web (7)
17. Most popular search engine (6,0)
18. Pretends to be something it’s not (6)

Down

1. Tries to damage your computer, delete files and sends messages (5)
2. Connects devices together to share data (7)
3. Portable and used to store data (6,5)
5. Stops other people getting on the network (8)
6. Tells you what an email is about (7,4)
7. A book for recording the names, addresses, and telephone numbers of friends (7,4)
10. Stops people getting into your computer (8)
13. Software that is specifically designed to disrupt, damage, or gain unauthorized access to a computer system (7)
14. Finds security loop holes and enters your computer (4)
16. Messages distributed by electronic means from one computer user to one or more recipients via a network (5)