In English, ordinal numbers are used to indicate the position or rank of something within a sequence. Here are the ordinal numbers from 1 to 20, along with a brief explanation of their usage in a context:

1. First: This ordinal number indicates the beginning or the highest-ranking position in a sequence. For example, "He came in first place in the race."

2. Second: It denotes the position that follows immediately after the first. Example: "She was the second person to arrive at the meeting."

3. Third: This number signifies the position that follows the second. In a contest, the third-place winner is the one who ranks below the first and second winners.

4. Fourth: It represents the fourth position in a series. For instance, "The fourth chapter of the book is particularly interesting."

5. Fifth: The ordinal number for the position that comes after the fourth. Example: "The fifth anniversary of their marriage was celebrated with a grand party."

6. Sixth: It marks the sixth position in a list or sequence. In sports, the sixth seed might be the sixth-ranked player or team.

7. Seventh: This ordinal number is used for the seventh position. For example, "The seventh day of the week is Saturday."

8. Eighth: It indicates the eighth position. In a music competition, the eighth contestant might be the one performing next.

9. Ninth: This number is for the ninth position. The ninth month of the year is September.

10. Tenth: It represents the tenth position. The tenth anniversary is a significant milestone to celebrate.

Continue reading for the ordinal numbers 11 to 20... (Due to space limitations, the remaining numbers will be briefly listed):

11. Eleventh, 12. Twelfth, 13. Thirteenth, 14. Fourteenth, 15. Fifteenth, 16. Sixteenth, 17. Seventeenth, 18. Eighteenth, 19. Nineteenth, and 20. Twentieth.

These ordinal numbers help us express the order of items, events, or people in a clear and precise manner.