Why some coinbase transactions have very long extra field, and some short?

Question

Wondering what is the difference between coinbase transactions. For example, this coinbase transaction has short extra field:

• https://moneroexplorer.com/tx/0abf00d51d051c0854d7715ceabdc518c07104434a01658a9dc53417a7dbbdf7

016e823f579828d0247e7f4f86deb9189923ca2b97d42bde8e77dfebe24b8217d60208000000025495d62b

On the other hand, this transaction has long extra field:

• https://moneroexplorer.com/tx/36f88dc165ac4192dd217472e993fdf566cbc6a93d55ea84f3b092b198ab8737

011387342c514195795e3088503cbac8b1f947db67a567933dc688faf20756f81f021d3951c73f000000004d696e6572476174653030310000000000000000000321003ed59fbae2a8aacb71a9e41639927beaa45e4b50c0d95ef1c8fd640fc74729f9

Why is there a difference in the length, and what is the extra data?

Answer 1

Because miners are free to put whatever they want in there.

For example, if you parse the 2nd as ASCII codes, it can be decoded to:

4,QAy^0P<ºÈ±ùGÛg¥g=ÆúòVø9QÇ?MinerGate001!>պ⨪Ëq©ä9{ê¤^KPÀÙ^ñÈýdÇG)ù