ICs are integrated circuit with complexity varying from simple to highly complex. Generally these integrated circuits are application specific and hence in electronics industry it is also referred as ASIC (application specific integrated circuit).

You can find ICs for simple AND gate, a small IC containing 4 two-input AND gates to complex micro controller and processors. Since these ICs are very specific to the applications their functionality can't be discussed in general. IC manufacturer and designer generally provide data sheets, these data sheets provides information about IC functionality, pins, voltage specification etc. Always refer IC data sheet for using it.

Now we will discuss some points which are general but can be very useful..

1. Before implementing any huge logic using discreet components, always check if an ICs is available for similar function. For example, you can build good audio amplifier yourself using discreet components such as transistor, capacitor and resistors. But after small search, you may find good amplifier ICs already available, this can save lot of time.
2. Since these ICs are functional block you don't have to worry about their internal logic, just refer their data sheet and straight use them.
3. Proper care should be taken while soldering ICs, overheating due to soldering can damage an IC permanently.
4. If you are not very confident on your soldering skill then it is a good idea to use "IC socket", these "IC sockets" will protect your ICs from soldering heat. Make sure that IC should not be in "IC socket" while soldering socket.
5. Static charge may damage your IC, hence always use anti-static strap while working with ICs.
6. Make sure to conform input voltage and power rating range of IC, applying large voltage or drawing large current will damage your IC.
7. Make sure you are using correct pin number reference as in the data sheet, always start counting pins from left of notch, as shown in the image below (this is top view of IC).
   

1. Very Compact in size.
2. Modular, due to this functions are encapsulated which results easy design, and less debugging.
3. Because of their small size, they save lot of valuable circuit board space.
4. power efficient, the ICs are designed to consume less power.
5. IC manufacturer, provides details about ICs behavior with various temperature range. This helps in estimating working temperature range for a system.

1. If the IC goes bad, there is no way to repair it.
2. ICs are very sensitive to high temperature, and can go bad if under soldering iron for long time.
3. Gets easily damaged due to static charge.