How to interpret asset transactions data for a NFT?

Question

Using the blockfrost API I quired the transaction history of a NFT using the following script:

from blockfrost import BlockFrostApi, ApiError, ApiUrls


api = BlockFrostApi(
    project_id='my_secret_key',  
    base_url=ApiUrls.mainnet.value,
)

try:
    health = api.health()
    print(health) 

    assets = api.assets_policy(my_policy_id)
    asset_history = api.asset_transactions(assets[13].asset, return_type='pandas')
    print(asset_history)

except ApiError as e:
    print(e)

Getting this response:

                                              tx_hash  tx_index  block_height  block_time
0   38ad1c10fce2ff3cc19a47002ea3f0e42257a56d051dc3...         2       6436806  1635591940
1   c379a46550f041e3dd25d534034beb71b04f15ce3f65b1...         7       6439385  1635644577
2   d92447f19d78cae77b57d727ee459e2665839990418233...        37       6439387  1635644654
3   1c6e774d35c6196d6236f0465ca162a5b873a846b2a5eb...        13       6439391  1635644697
4   5c1048c319fcfca8ba8f6992ae894be73c9244d78d9947...        18       6439398  1635644851
5   f71f698da38403c475565c109a143bda06fb87f718ec08...        34       6439401  1635644928
6   e15fb6c7fdc5ccc6ccef234f0645b510f150bf7b2e74b4...        18       6439533  1635647419
7   479995eea8a566384eec7b8933c55ef83db42b08779538...         2       6440258  1635663466
8   0548dab5b72458d0ea31b0e99f13c671d4634d27657e03...         0       6440355  1635665472
9   94141bcb58cdb5822b9fea7eab9b8868845d523f9f190d...         8       6441301  1635685169
10  738bed4f7bccfa426a403e35845bee96c0d3f41e83ea5e...        13       6441422  1635687392
11  4afb4df1d193ceb3bfe24d9de934252a176120888e0a96...         0       6442330  1635706804
12  4e847c23f326821b3565472045e36ea774f496df2f09a5...        70       6442428  1635708878
13  cb19e1da6665375c1b6b3ac1e0e31bb238b1f1c90000f3...         6       6444826  1635758501
14  6ec8b61254f82120c6120a24d41e50977abf613f5c66b7...        23       6445035  1635762659
15  5e644b9c77d6c565c925d15cfecfffd7a279eb9a2c713e...        31       6447594  1635814038
16  8db58815ee4ad5f37aaaddbd7d1ef8719477a87d24452d...         4       6447605  1635814237
17  11fd5b552be255831d82fdc513fff41c4809cf33e7c6b2...        12       6447776  1635818167
18  b05dd10d64764ae7b9aab93c3b1e7ddaa2a6c9c0680461...        26       6462608  1636121671
19  22a8c33a6fe35fd82cfd00544bda4345ea65318188a927...        25       6462612  1636121753
20  f9882f6aea766d9f5a3b503f168c84b635e9be0a349acd...         7       6462673  1636122903
21  0a6fa23b9081d938e986734071ab66c7032f6c50954428...        22       6462904  1636128077
22  8450c04442ba42432edc4d7d1c703e084e28e6ab3e9f8d...         4       6463391  1636138353
23  ade1f612f6d7adcb54c3a804cdb230f343b486f425f32c...         0       6468943  1636250015
24  13fb4e318ba12558819ede20ed37dc2bef7b9dae7cff61...        26       6469165  1636254523
25  3153d200935012eb695ffafd13ffe68c04c4f2fc179c9a...         4       6469171  1636254605
26  fb5e69b4ddb00f23cbe879c2087fe315178ac73fa07c56...        22       6469172  1636254670
27  9555c42315f15a88b29535ebffc05369ccc9b2fc092db8...         4       6482371  1636529118
28  09e430ad3ffde4f1e21fe33564f29a0fbb699213df67f8...         9       6483131  1636544549
29  8949eed31b7cede95c294f0bdec3d6b26ded6b14a18adb...        35       6485203  1636585696
30  50a06e0f0cc53e666d474798f5bc05bffcc1812fd23524...        31       6485216  1636585952
31  e0401628a403a699d91610439606f406d82c9fa4cf655f...        28       6485336  1636588252
32  89a311b10d004da25b3027d4795fc2e245a59a6be30c5e...        54       6485341  1636588391
33  e7b5c1b24ae39bf0f10000237bee03254ea0ac67399002...        16       6485394  1636589435
34  3a319385fe7a8373e3c0ac864727147ccb3edb409abac8...         8       6485404  1636589609
35  7f4a9bd753caae61e6e7e7147269ab6500832aab8d786c...         8       6485406  1636589642
36  1b0965031f3e137f9d787941230894ccf91d89d0beb6b9...        20       6485430  1636590112
37  f526d275da39c46783983aa326da5fe13379270ab12b01...        13       6485447  1636590324
38  cbe3b65fd19364fab8e69062d9075dfa9f6ff90e25f02b...        26       6488527  1636651538

My questions:

• Does each line represent a transaction where the NFT was transferred from one address to another address? If not, why are there so many transactions?

• What is the tx_index?

• Is the block height simply the size of the new block added to the ledger? (in bytes?)

• Where can I find a reference so that I can easily answer these questions myself and not have to create a StackOverflow post each time?

Answer 1

• Correct, that is the history of transaction of that specific asset
• That is the index of the transaction within a block
• block_height is the height of the block, in other words, it is the number of the block in the blockchain
• Directly on docs.blockfrost.io, go to the specific endpoint and click on the 200 response to roll down the descriptions of each fields: