Temperature + humidity sensor
This is a temperature/humidity sensor. You can use this Arduino compatible sensor to monitor the ambient temperature or humidity. As a basic project, you can plug an LCD to Arduino and have it display the room temperature/humidity.
Infrared emission sensor
This is an infrared emission sensor, also called "infrared emitting diode". It works at 38KHz modulating signal. This sensor can be used to send code to another Arduino or control a TV.
Photoresistor
This a Photo Light Sensitive Resistor. The resistance of the component will vary with intensity of light to which it is exposed. Explained in simple term we will say that this sensor is a resistor whose resistance goes down when light hits it.
Ultrasonic Distance sensor
This sensor automatically sends an audio signal of 40 kHz and detect whether there is a pulse signal back. It sends a signal and if received back it computes the distance traveled by the signal, thus the distance from the sensor to the object in front of the it. It can sense an object in the range: 2cm~500cm
Knock sensor
In simple terms, this is a switch that turns on when it detects a knock. There is an LED that alternatively gives a visual signal of the state of the sensor, high or low, and the high level designated by the LED turning on
Sound sensor
This is a sensor that will detect the surrounding sound, and it has a adjustable sensitivity. This is best used for projects such as voice changers.
Flame sensor
This sensor detects the presence of flame and is often be used to detect the presence of light as well. It detects a flame or a light source of a wavelength in the range of 760nm-1100 nm. A light flame test can be triggered within 0.8m. If the intensity of flame is high, the detection distance will be increased
