What all the addresses are in my Electrum wallet? What are addresses mean in Electrum? Are they some default/predefined/popular addresses? Are they all my BTC addresses?

Can I delete them entirely? I couldn't find delete option, only freeze.

Why are some green receiving and some yellow change?
They are indeed all your addresses. The addresses labeled receiving in green are meant to be given to people from whom you wish to accept a payment and the yellow change addresses are there for Electrum to use when you make a transaction with an unspent output.

About receiving addresses

Using a separate address for every incoming transaction is better than using the same address all the time for a couple of reasons:


It increases your privacy. If you used only one address, all your transactions and your balance would be easily known to everyone who knows your address, so for everyone who has ever paid you or received a payment from you. If you use different addresses, it's much more difficult to relate the different transactions to the same person.
It allows you to discern between different sources of funding. Because in Bitcoin there is no "transaction title" or any other description, if you simultaneously await two payments, let's say for the same amount, you would have no way to know who paid you if not for having given different addresses to different payers.


If you want to use an address multiple times, as for example if you publish a donation address on your website, you can do it of course, Electrum won't stop you. In some cases it's not a problem at all, but you have to understand that you sacrifice a little bit of your privacy, e.g. other people can find out what's your balance on this donation address. just It's useful to label any address you use (publish or give to anyone) so that you know where from each transaction comes.

About change addresses

The change addresses work like this: let's say you have an address 1Abc with 0.5 BTC and another address 1Xyz with 0.5 BTC. Now you need to pay someone with an address 1Pay 0.7 BTC. Electrum would handle this by creating a transaction with inputs from addresses 1Abc and 1Xyz (which sum up to 1.0 BTC) and the outputs would be 0.7 BTC to the address 1Pay and 0.3 BTC to the address 1ChA, which is one of your change addresses. Each change address is used only once. The reason for the existence of change address is the same as reason 1. above: it increases your privacy.