Recent researches and advancement in the wireless communication and electronics field have led to the development of low-cost, low power sensor nodes which are small in size and can communicate with each other even at short distances. These small size sensor nodes, which consist of sensing, communicating and data processing capabilities, give the idea of sensor networks. Wireless sensor networks represent great improvement over traditional networks.
A sensor network is composed of large number of sensor nodes which are distributed in the wireless environment. This feature allows a random distribution of the nodes in the disaster relief operations or inaccessible terrains. Another unique feature of sensor nodes is the cooperative effort of sensor nodes. It means that sensor nodes perform distributed operation and co-operate each other to perform a single task. Sensor nodes in the WSN are fitted with an onboard processor. Instead, of sending raw data to the nodes responsible for fusion, they use their processing capabilities to carry out simple computations locally and transmits only the required and partially processed data. 
Thus due to these features of wireless sensor networks they have a wide range of applications . These applications  include environmental control such as fire fighting or marine ground floor erosion, also installing sensors on bridges or buildings to understand earthquake vibration patterns, surveillance tasks of many kinds like intruder surveillance in premises, etc. Also classes of applications include car-to-car or in-car communication. The possibilities abound ââ‚¬" sensor networks could potentially become a disruptive technology when the basic size and cost problems are solved.
As sensor networks are infrastructure less networks similar is the case with mobile Ad-hoc Networks (MANETS). These both types of networks looks to be same in properties but there are a lot of differences between them. The Comparison between Sensor networks and MANETS can be explained as follows:-
1.2 Comparison of MANETS and Wireless Sensor Networks (WSN) 
MANETS (Mobile Ad-hoc Networks) and sensor networks are two classes of the wireless Ad-hoc networks with resource constraints. MANETS typically consist of devices that have high Capabilities, mobile and operate in coalitions.
Sensor networks are typically deployed in specific geographical regions for tracking, monitoring and sensing the surrounding environment. Both these wireless networks are characterized by their Ad-hoc nature that lack pre-deployed infrastructure for computing and communication. Both Share some characteristics like network topology is not fix, power is an expensive resource and nodes in the network are connected to each other by wireless communication links. WSNs differ in many fundamental ways from MANETS as mentioned below.
Sensor networks are mainly used to collect information while MANETS are designed for distributed computing rather than information gathering.
Sensor nodes in the sensor networks mainly follow broadcast communication technology but most MANETS are based on point-to-point communications.
The number of nodes in sensor networks can be higher in several orders than that in MANETS.
Sensor nodes may not have global identification (ID) because of large number of sensor nodes and large overhead while nodes in MANETS have global-ID.
Sensor nodes are much cheaper than nodes in a MANET and are usually deployed in thousands.
Sensor nodes are limited in computational capacities, memory and power whereas nodes in a MANET can be recharged somehow.
Usually, sensors are deployed once in their lifetime, while nodes in MANETS move really in an Ad-hoc manner.
Sensor nodes are much more limited in their computation and communication capabilities than their MANET counterparts due to their low cost.