2. processor  :
The "brains" of your Laptop, the processor has a huge influence on performance, but depending on what you want to do, even the least-expensive model may be good enough.Finding the right chip is hard. Intel’s processor ecosystem is strewn with confusing model numbers that actually tell you a lot about the processor you’re about to buy.
you would get the specification as INTEL CORE I7-7500 U
"intel core" represent "The Brand" :Around 90% processors in laptop have intel core
" I7 " represent "The Family" Of the laptop : Most common are I3 , I5 and I7
" 7 " represent "The Generation " Of the laptop: the more higher the number is the more new is the laptop in the market
" 500 " represent "The range" :The more higher the range ,more powerful is the laptop
" U " represent "The suffix" : They are five different type of suffixes as U,Y,H,HK,HQ.Each sufix has it meaning
If you want a plain and simple answer, then generally speaking, Core i7s are better than Core i5s, which are in turn better than Core i3s. Core i7 does not have seven cores nor does Core i3 have three cores. The numbers are simply indicative of their relative processing powers.Their relative levels of processing power are based on a collection of criteria involving their number of cores, clock speed (in GHz), size of cache, as well as Intel technologies like Turbo Boost and Hyper-Threading.
Y-Extremely low power represented as i7-7Y75 : this is used in cheaper laptops or light-weight laptops
U-ultra low power represented as i5-7200U : this is genrally used in normal laptops
H-High performance represented as i3-6100H
HK-High performance unlocked represented as i7-6820HK
HQ-High performance quadcore represented as i7-6700HQ : used for high gaming purpose
There are many thing such as number of cores ,cache ,hyper-threading,clock speed which should be considered while taking a look into the processor
Each core is effectively its own processor – your laptop would still work (slowly) with just one core enabled. Having multiple cores means that the Laptop can work on more than one task at a time more efficiently, which will help keep your system running faster even if you have tasks, such as an antivirus scan or video render, running in the background.Having several cores can also drastically increase the speed at which certain programs run. Dual core would be enough if you won't run too many applications and tabs at a time.Too run to many applications at a time prefer a Quadcore.
Hyper-Threading essentially tricks Windows into thinking that each physical processor core is in fact two virtual (logical) cores. The operating system can then share processing tasks between these virtual cores in order to help certain applications run more quickly, and to maintain system performance when more than one application is running at once. a Core i5, which is only a dual core serving two threads per core. In other words, a total of four threads can run simultaneously. Thus, even if Core i7 with a quad cores,which don’t support Hyper-Threading the number of threads they can serve at the same time is just about equal to those of their Core i5 counterparts but they don't double the speed, but a useful boost nonetheless.
The speed at which your laptop runs programs or completes tasks is determined in great measure by your laptop processor speed. Processor speed is measured in gigahertz (GHz). The higher this measurement, the faster the processor. For example, let’s say you’re comparing two Intel Core i5 CPUs, which only differ in their clock rate. One runs at 3.4 GHz, and one runs at 2.6 GHz. In this case, the 3.4 GHz processor will perform 30% faster when they’re both running at their top speed. This is true because the processors are otherwise the same. But you can’t compare the intel Core i5’s CPU clock rate against another type of CPU, such as an AMD CPU, ARM CPU, or even an older Intel CPU,they can be compared only in same family. it is represented as 2.5 to 3.1 GHZ,which means that it would normally run at 2.5 GHZ but if required it can increase its speed to 3.1 GHZ by using turbo boost. See that you find with 2.7 GHZ or more for better processing
Turbo Boost   :
It dynamically increases the clock speed of Core i5 and i7 processors when more power is required. This means that the chip can draw less power, produce less heat (most of the time) and only boost when it needs to.The maximum amount that Turbo Boost can raise clock speed at any given time is dependent on the number of active cores, the estimated current consumption, the estimated power consumption, and the processor temperature.It is generally not present in I3-core processor
Whenever the CPU finds that it keeps on using the same data over and over, it stores that data in its cache. Cache is just like RAM, only faster — because it’s built into the CPU itself. Both RAM and cache serve as holding areas for frequently used data. Without them, the CPU would have to keep on reading from the hard disk drive, which would take a lot more time.A larger cache means the chip will need to grab data RAM less frequently, leading to faster performance.Basically, RAM minimizes interaction with the hard disk, while cache minimizes interaction with the RAM.The minimum amount of storage in an i3-core processor is of 3-4 MB and in i5,i7 it goes upto 6 to 8 MB.
The upshot is that if you do a lot of things at the same time on your PC, then it might be worth forking out a bit more for an i5 or i7 because
they have good number of cores,clockspeed and cache . However, if you use your laptop check emails, do some banking, read news,watch movies, download musics,low end softwares you might be equally served by the cheaper i3 core.
RAM stands for random-access memory.Your laptop RAM is essentially short term memory where data is stored as the processor needs it. This isn’t to be confused with long-term data that’s stored on your hard drive, which stays there even when your laptop is turned off. Anytime you play a game from your laptop's hard drive or stream a movie from the Internet, all of the data that your Laptop's processor needs to play the game or watch the movie is stored in RAM. This is so that your processor can get to it quickly. Once you’re done playing your game or watching your movie and you close it down, the processor doesn’t need that data anymore, so it replaces it with the next task you give it. RAM can slow down your Laptop if there isn’t enough of it for the processor to perform the tasks you ask it to. If your processor wants to load more data than your Laptop RAM can handle, it has to keep going back to the hard drive or the Internet to obtain the information again. Laptops also come with 2GB of ram but atleast 4 GB of ram is ideal.With 8GB, you can multitask a lot better, keeping dozens of tabs open in your browser while watching a movie, playing a game and editing email. Check whether the laptops has ability to update the ram, Not all machines can take an upgrade.nowadays if you ask for a laptop of 8GB ram in a offline store ,they give you a laptop with 4GB ram and additional 4GB is added externally to make it 8GB doing this would reduce the price . Prefer a DDR4(Double Data Rate Fourth Generation) specification RAM as it is the latest generation which have a higher speed to fetch the data .It is the higher version of the DDR3 but with a lesser voltage requirement of only 1.2 volts. Compared to DDR3’s 1.5 V, it operates a frequency ranging from 2133 MHZ to 3200 MHz and it also has a higher data rate transfer than its previous versions.
4.  operating system:
An operating system is the most important software that runs on a computer. It manages the computer's memory and processes, as well as all of its software and hardware. It also allows you to communicate with the computer without knowing how to speak the computer's language.The laptop's can come with operating system preinstalled or DOS(disk operating system) .DOS mean there is no OS present and you need to get it added,this can be done at any computer service center and it would cost you a very few bugs rather than taking a preinstalled OS laptop. There won't be any difference between the preinstalled version and a external added version. Check that your laptop has a compatibility to upgrade to even other OS(if you require) ,some laptops work only on a particular OS. The different types of OS are Windows,MAC,Linux,Ubantu,Chrome.Take the one which you're familiar with.
5.  graphics card:
The graphics card in your laptop converts video data into electronic signals and sends them to your screen. The monitor accepts the graphics card signals and turns them into colorful images. The process happens fast enough to handle videos, games and other media. All laptops have some form of graphics card in an integrated form or a dedicated card form.
If you're not playing laptop games, creating 3D objects or doing high-res video editing, an integrated graphics chip will be fine.An integrated graphics card is bound to the motherboard and shares RAM with the CPU. So, if you have a computer with 4GB of RAM, the graphic card can use anywhere between one and five percent of the available memory for graphics processing. Of course, this percentage varies depending on the size of task, especially if you're multitasking or playing a game.
These integrated graphics are enough for windows and browser animations or maybe some games which are really old and do not require a lot of high frequency video ram. the intel processors model numbers ending ‘00U’ have basic Intel HD Graphics 620 chipsets, while chips ending ‘60U’ have the much more powerful Intel Iris Plus Graphics 640. There are also Core i3, Core i5 and Core i7 chips with the suffix ‘67U’, which are fitted with the top-of-the-range Intel Iris Plus Graphics 650 chipset.
A dedicated graphics card allows us to add additional processing power to graphically intensive tasks. If you have any of the above needs a dedicated graphics processor from AMD or Nvidia is essential. As with CPUs, there are both high- and low-end graphics chips. Low-end gaming or workstation systems today usually have Nvidia GTX 1050 while mid-range models have GTX 1050 Ti or GTX 1060 and high-end models have GTX 1070 or 1080. Nvidia maintains a list of its graphics chips from low to high end, as does AMD. A dedicated graphics is Perfect for Graphics Applications such as Photoshop,Essential for Video Rendering,to use a VR-set,Great for Gaming and have more power .
Not everyone needs a graphics card in their laptops, but for others it’s essential for a good computing experience. Which one you need really depends on you. If you use applications that would be considered “high graphics,” such as Adobe Photoshop, video editing software or any game, then I promise you that you will love having a machine with a graphics card in it. If, on the other hand, your usage is more basic and limited to email, Internet, and other basic functions , then there is simply no need for you to spend the extra money. An integrated graphics card also generates much less heat than a dedicated video card and uses drastically less power, which improves the overall battery life.
6. Storage   :
The photos,videos,applications and many other things which we need to access in future we store them up.The storage in latop's is of 2 types HDD(hard disc drives) or SSD(solid state drive)
In SSD the information is stored in microchips it relies on an embedded processor (or “brain”) called a controller to perform a bunch of operations related to reading and writing data. The controller is a very important factor in determining the speed of the SSD. Decisions it makes related to how to store, retrieve, cache and clean up data can determine the overall speed of the drive.
A Hard disk drive uses a mechanical arm with a read/write head to move around and read information from the right location on a storage platter. An HDD uses magnetism to store data on a rotating platter. The faster the platter spins, the faster an HDD can perform. Typical laptop drives today spin at either 5400 RPM (Revolutions per Minute) or 7200RPM.
An HDD might be the right choice if you need lots of storage capacity and don’t want to spend much money,don’t care too much about how fast a computer boots up or opens programs.An SSD might be the right choice if you are willing to pay for faster performance ,don’t mind limited storage capacity .If you are taking laptop for normal purpose rather than buisness operation prefer a HDD of atleast 1TB.
7. Display :
The picture on a computer display is made up of individual squares called pixels.
A screen’s surface would resemble a fine-mesh net if you looked at it under a magnifying glass. Each pixel can be one of 16.7 million (or more) colors. From a distance, the individual pixels aren’t distinguishable.The number of pixels on the display does matter. The count of pixels is called display resolution. It’s defined as the number of pixels wide by the number of pixels tall.
A 1,920×1,080 display, also known as full HD, has 1,920 pixels spanning horizontally, and 1,080 pixels vertically. This resolution is also called 1080p, the “p” standing for progressive, indicating the number of vertical lines in the display.A 1,366×768 display, also known as HD or 720p.QHD is 4 times of HD i.e. 2560 x 1440, (1440p). UHD or 4k UHD is 4 times of FULL HD i.e. 3820 x 2160,(2160p). Higher resolution screens are generally more expensive. If a FHD comes in your budget take it as you can get better clarity and display and these days Antiglare coating(non-glossy coating which reduces reflections and glare on the display) is coming on almost all FHD screens.The higher pixel consume more power, lowering your battery life.
Two specs to look for in laptop batteries include capacity (measured in milliamp hours, or mAh) and the number of cells. Typical batteries have a mAh rating of between 2000mAh and 6000mAh — higher is better.Batteries have a voltage rating (V) and milli-Amp hours (mAH), which, if multiplied together, give you milliwatt hours. For example, a 14.8 V battery with 4460 mAH gives you 66,000 milliwatt hours (66 watt-hours).the specification on battery is given in watt-hours(whr). Cells are the actual compartments where power is produced, and can range from 2 to 12 — the more the better. Make sure you get a Lithium Ion battery with maximum cells in the model you are looking for. You need to consider your lifestyle and decide how important battery life is to you and how much extra you’re willing to pay for a computer with a long-lasting battery. Factors that can increase battery life include LED lit screens, solid state drives, and low-power processors. These newer technologies consume less power, which is a far more convenient way to extend battery life than including a larger and heavier battery.
For long typing sessions, you must get a laptop that has a comfortable keyboard. You don’t want to get a keyboard that packs in every key under the sun (thin keyboards that have squished in number pads) because that can translate to a poor overall user experience when hunting for keys like the arrows.You want a keyboard that has a comfortable layout with full-sized keys and some space around the arrow keys. The keys should have adequate travel on the downstroke and rapid responsiveness when you let them go. Make sure the keyboard is also backlit, so that you can type with an easier view on the keys in dimly lit environment.Better have a hands-on the keyboard by asking to show a demo model.
You should get a laptop with a USB 3.0 port, and you should look for a laptop that has at least a couple of these ports. This is for obvious reasons such as plugging in an external hard drive to back up your laptop’s data, or for when you want to plug in a conventional mouse or a fancy keyboard. Check whether the laptop has the features like bluetooth connectivity,dvd drive ,webcam,sound quality ,warranty(ADP or NBD) ,antivirus ,fingerprint sensor if required .Buy headset , screen cleaning kit ,Laptop Bag,USB/optical mouse,keyboard and monitor screen cover along with the laptop.