|Centuries:||1st century BC – 1st century – 2nd century|
|Decades:||70s 80s 90s – 100s – 110s 120s 130s|
|Years:||97 98 99 – 100 – 101 102 103|
|100 by topic|
|State leaders – Sovereign states|
|Birth and death categories|
|Births – Deaths|
|Establishment and disestablishment categories|
|Establishments – Disestablishments|
|Ab urbe condita||853|
|English Regnal year||N/A|
— to —庚子年十一月十三日
|- Vikram Samvat||156–157|
|- Shaka Samvat||22–23|
|- Kali Yuga||3201–3202|
|- Ǹrí Ìgbò||-900–-899|
|Iranian calendar||522 BP – 521 BP|
|Islamic calendar||538 BH – 537 BH|
|Juche calendar||N/A (before 1912)|
|Julian calendar||100 C|
|Minguo calendar||1812 before ROC
|Thai solar calendar||643|
|Wikimedia Commons has media related to: 100|
Year 100 (C) was a leap year starting on Wednesday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Traianus and Frontinus (or, less frequently, year 853 Ab urbe condita). The denomination 100 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years.
By place 
Roman Empire 
- Emperor Trajan and Sextus Julius Frontinus become Roman Consuls.
- Bricks become the primary building material in the Roman Empire.
- Pliny the Younger advances to consulship, giving his panegyric on Trajan in the process.
- The Roman Army reaches 300,000 soldiers.
- Tiberius Avidius Quietus' rule as governor of Roman Britain ends.
- Timgad (Thamugas), a Roman colonial town in North Africa is founded by Trajan.
- Trajan creates a policy intended to restore the former economic supremacy of Italy.
- Pakores (last king of the Indo-Parthian Kingdom) takes the throne.
- Paper is used by the general populace in China, starting around this year.
- The Kingdom of Himyarite is conquered by the Hadramaut.
- The Hopewell tradition begins in what is now Ohio circa this date.
- Teotihuacan, at the center of Mexico, reaches a population of 50,000.
- The Moche civilization emerges, and starts building a society in present-day Peru.
By topic 
Arts and sciences 
- In China, the wheelbarrow makes its first appearance.
- Main hall, Markets of Trajan, Rome, is made (until 112).
- Appearance of the first Christian dogma and formulas regarding morality.
- The Gospel of John is widely believed to have been written around this date.
- The compilation of the Kama sutra begins in India.
- The Temple of the God of Medicine is built in Anguo, China.
- The Fourth Buddhist Council is convened circa this year.
- Justin Martyr, Christian apologist (approximate date) (d. c. 165 AD)
- Marcus Cornelius Fronto, Roman grammarian, rhetorician and advocate (d. 170)
- Agrippa II of Judea (b. 27)
- Josephus, Jewish historian (b. 37)
- John the Apostle of Jesus Christ (b. 6)
- Asimov's Guide to the Bible, page 954.