1. no doctype
2. lang not language
3. no metadata
4. Two opening HTML tags
5. h1 closing tag missing
6. no opening p tag
7. mismatched ol/ul tags
8. Missing closing p tag
9. Closing img tag instead of closing a tag
10. No alt text in img
11. source not src
12. Unclear whether or not the image is supposed to be linkable, I made it so because I think it makes more sense for "click me" to guide user towards image click
13. No closing table tag
14. No center tag in HTML5, must use css
15. No bgcolor attribute in HTML5
16. comment left open
17. link missing closing tag
18. mis-nested em and p tags
19. em tag where it should be a u
20. li in a descriptive title; should be dt
21. li in a descriptive list description; should be dd

Welcome to My Error-Filled Page

This is a paragraph with mismatched tags and missing closing tags.

1. Item 1
2. Item 2
3. Item 3
4. Item 4
5. Item 5
6. Item 6
7. Item 7
8. Item 8
9. Item 9
10. Item 10

This is another paragraph without proper indentation.

Text

Underlined text

Descriptive Item Title

Descriptive Item Text