Hardware Component:

It is a fundamental part of IOT systems, formed by sensors of any parameter 
that is necessary to measure

Special attention will have to be given to the environment in which this sensor 
will be exposed, as one 
of the characteristics of IoT systems is that they must operate 24x7x365

It is important to consider the possibility of updating the system in the face of software 
changes and improvements, 
there are many devices and therefore the remote update must be considered,
 if you lose sight of the security that can always be threatened before this possibility

The communications network: Gsm, Wifi etc. 
must ensure continuity of service without cuts

Security is an important aspect and guaranteeing
 some type of encryption is a factor to consider

Last but not least, the software-server (usually Cloud) in charge 
of collecting, classifying and making sense of the large amount 
of data generated by this type of system.

Only when this information is properly managed, 
is it when the IoT makes sense and offers incredible 
possibilities.