What is the official website for bitcoin? bitcoin.com or bitcoin.org
Are other websites linked to bitcoin? What about bitcoin.info, bitcoin.help, crypto.com, blockchain.com?
What is the official website for bitcoin?
Bitcoin isn't a lawful entity but a collection of interoperable stuff.
Bitcoin.org is registered by the creator of Bitcoin and currently managed by Cobra, who is a controversial person but doesnt seek profit from it
Bitcoin.com is owned by Roger Ver, who is interested in promoting Bitcoin Cash as Bitcoin. The website is supported by Bitcoin Cash fans and hated by Bitcoin users. (Citation needed?) You just need to be careful, what they have on their website Bitcoin Cash will not be applicable to Bitcoin. It might happen that "your transaction can't be found" because you're on their Bitcoin Cash explorer. When you're sure that you chose the correct coin, there is no downsides of using it.
There is no official website for bitcoin.
Bitcoin is a decentralized network, with no admins, no hierarchy, no leader. This is not what you might first expect, but it is the truth, and necessarily so: if bitcoin had a leader, they would constitute a central point of control, which would negate the properties that make bitcoin interesting in the first place!
This can be confusing to new-comers, after all, where will you go to find good information? To find good software? Especially since the wider 'cryptocurrency' ecosystem is rife with scammers and abuse. My advice would be to not trust any single source of information-- instead, do your own research, using many independent sources, until you feel comfortable that you understand what you're doing. Its tough to trust just one website for information, but if you see 100 websites all independently reporting the same information, then you might find yourself getting closer to the truth.
At a more pragmatic level, the software that is run by a majority of the network peers ('full nodes') can be found here: Github link. But there are other full node implementations as well, such as bitcoin-knots, or btcd. Again, there is no 'official' implementation, the project is open source, so anyone can build and contribute to it, though the bitcoin-core software linked above is the most popular and most widely utilized of the available options (and, importantly, perhaps the most well-reviewed, which helps to ensure it is secure).
As MCCCS mentioned, bitcoin.org is well-regarded in the community, as it is run by many of the same contributors that maintain the bitcoin-core software. But don't take my word for it! Find corroborating sources, verify for yourself that what I'm saying is true.
This sort of "don't trust, verify" attitude is important when dealing with bitcoin. With no leaders, there is no need to really trust anyone, after all.