It’s a very good question, and one that gets asked several times a month. So we have not one but two community FAQs about it. Those should answer your basic questions.
Start with the short FAQ, and then if you want more details on the various problems and issues, look at the long FAQ. ( The topic titles are clickable links)
Although the topic title may mention Hue, it applies to any brand of smart bulb.
And
After you read those, if you still have any questions, you can add them here. But please read the FAQs first.
Those should answer your basic questions.