Components are nothing but a UI properties that are available for building app UIs.React Native components are native components.They support both Android and Ios.

Basic Components:

View
Text
TextInput
Button
Image
ImageBackground
TouchableOpacity
TouchableHighlight
ScrollView
ListView

View:

View is a section or a container or a layout of page.
If a page contains more than a single component, than it should be wrapped within a view.

Text:

Text Component is to display text elements in the app.
Elements like Headings, Labels etc will be displayed using Text Component.

TextInput:

TextInput Component used to get user input in the app.
It is an Input component with several props.

Button:

Button components used for event triggering.
onPress props used to bind a function that triggers while pressing button.

Image:

Image Component used to display images.
Image component contain two types of source
One is for local image and another for server images
Local image is assigned to source by giving image src
Server side image source is assigned with weblink

ImageBackground:

Imagebackground is used to set background image for a layout or view.
Like image both image and server image source is supported on ImageBackground.

TouchableOpacity:

TouchableOpacity is similar as Button Components.
It gives a touch effect so that user can feel the touched the button.
The onPress used to bind the function that triggers while pressing the TouchableOpacity.

TouchableHightlight:

TouchableHighlight is similar as TouchableOpacity.
TouchableOpacity can wrap multiple Component inside it.But TouchableHighlight cannot wrap any components.

ScrollView:

ScrollView is a basic components which are available in all other frameworks.
ScrollView displays the layout which exceeds height of the original layout height.User can scroll the layout to view the full layout without missing.

ListView:

ListView component used to display list of data.
For example if you want to display a contactlist , Listview will be a suitable component for you.