>>132930802Radicals are components of kanji, e.g. 明 is composed of 日 and 月.
There is the strict definition which assigns to each kanji only one of its components as its radical, but this definition is only useful for classifying purposes (it's like their alphabetical order). Around here it's often used as a synonym for component. Furthermore, there is an official list of some 200+ radicals, but in practice a lot of components you see all of the time are not even in this list, so lets forget about the strict definition and talk about components, which is what you should really be worried about.
You don't have to learn them individually if you don't want to, you'll eventually pick up on them as you see them. For example, 待, 時 and 持 are three extremely common kanji which share the temple component (寺). You'd learn them early on and soon realize they are conspicuously similar.
That doesn't mean you should just get used to them and forget about it. Components hint at the meaning and sound of a kanji and are thus an indispensable tool when memorizing them. Learning components individually wastes too much time with little to no payoff though, so I'd suggest you just look them up as you come across them.
As an example, look at 持 again. The thing on the right is the temple radical, as I said. The left component is the hand radical. Usually, when kanji components are organized in this left-right disposition the left one hints at the meaning and the right one hints at the on'yomi (Chinese derived pronunciation of the character). 持 means roughly "hold" or "have", which is hinted at by the hand, and its on'yomi is "ji", which is hinted at by the temple radical because characters with "temple" as their sound indicator are pronounced "shi" or "ji". (That's not to say that every character with "temple" in it is pronounced like that, 等 has temple at the bottom but it's pronounced "tou").
