Page 52 - Big Data Analytics for Connected Vehicles and Smart Cities

32 Big Data Analytics for Connected Vehicles and Smart Cities What Is Big Data? 33

Like all data, big data is measured in bytes. A byte is eight bits, and a bit
represents either a one or a zero, otherwise known as binary or numbers to the
base 2. This numbering system is useful because switches in a computer can
be turned off to represent 0 and on to represent one. The term bit is short for
binary digit and can be considered the smallest unit of data in a computer. You
might also like to know that half a byte is called a nibble. In telecommunica-
tions and Internet traffic, the speed of the connection is usually described as the
number of bits per second. This is often referred to as bandwidth, although it
describes the speed rather than the capacity of the communication channel. An
ASCII character, one of the characters used to build the words in this sentence,
consists of one byte.
As data sizes have grown, prefixes have been placed in front of the byte to
represent multiples of 1,000. Table 3.1 [1] shows what these prefixes mean in
terms of the number of bytes; and to provide some context, it includes notes to
relate the sizes to something recognizable. For example, if you know that a data
size is 4 Zb, it is hard to comprehend. If you know that annual global Internet
traffic is expected to pass the zettabyte threshold by the end of 2016 and will
reach 2.3 Zb by 2020 [2] then you can start to comprehend the enormity of
the number.

3.5 What Is Big Data?

Big data is a widely used term, and it is important that we have a clear and com-
monly agreed on definition of the subject. Big data describes data sets so large
and complex that they become difficult to process using conventional data-
processing hardware and software. There is a trend toward assembling larger

Table 3.1
Orders of Magnitude of Data [1]
Size and prefix Base 10 Notes References
1,000 bytes = 1 kilobyte 3
1,000 kilobytes = 1 megabyte 6 A typical English book volume in plain [3]
text
1,000 megabytes = 1 gigabyte 9
1,000 gigabytes = 1 terabyte 12 212 DVDs [1]
1,000 terabytes = 1 petabyte 15
1,000 petabytes = 1 exabyte 18
1,000 exabytes = 1 zettabyte 21 Internet traffic in 2016 [2]
1,000 zettabytes = 1 yottabyte 24
1,000 yottabytes = 1 brontobyte 27
1,000 brontobytes = 1 geopbyte 30