Notebook and laptop computers are personal computers which unite a display, keyboard, speaker, and tactile directive interface (e.g. touchpad, touchscreen) into a portable unit. Regarding computers, the terms 'notebook' and 'laptop' are synonymous.

Operation

Laptops are programmable machines which execute a specific series of digital commands to accomplish a task. Laptops operate in a manner similar to desktop computers, as they require the same components to process, store, and display information.

The main advantage of a laptop is a compact form factor, facilitated by an integrated, hinged display. They have a smaller footprint, typically weigh between four and eight pounds, and can be transported in common toting articles, such as a briefcase or schoolbag. These abilities often come at the expense of computing power and data storage capacities.

Other advantages and disadvantages exist, as articulated by the accompanying table.

Components

Laptops require the same hardware and software infrastructure as a desktop, but make more creative use of the designated space.

Hardware

Central processing unit (CPU)

The CPU executes commands and is the most critical component of the computer. It consists of the arithmetic logic unit (ALU), which calculates mathematical equations and logic functions, and the control unit (CU), which determines commands and delivers them to the ALU from the computer memory. Registers may also be included, which act as short-term, local memory for the CPU. The CPU is connected to other laptop components through electrical buses. CPUs designed for laptops are usually more energy efficient and less powerful than CPUs meant for desktops.

It is common to create multicore processors which deliver two or four CPUs within a single chipset. This significantly enhances calculation speed. The rate at which the CPU completes calculations is known as clock rate and is measured in hertz. The clock rate can be determined by multiplying the memory bus speed and the multiplier of the processor. Processor names often contain a number and by moving the decimal two digits left the multiplier can be identified. For example, for a Pentium II 450 the multiplier would be 4.5. Intel®, AMD®, NVidia®, and GlobalFoundaries® are amongst the leaders in processor development.

Random-access memory (RAM)

This type of memory allows the computer to access the bytes for which it is seeking without sorting through other data. This information is more easily recalled than data that is saved to a hard drive. As such, it greatly contributes to the speed at which the laptop completes calculations and accesses software. RAM capacities for laptops are 32 GB, while desktops are capable of substantially higher totals.

Power supply and battery

Laptops are connected to a power supply via DC connecting cables. These cables also recharge a removable lithium-ion battery which can power a laptop for a limited time when not connected to an external power source. However, the charge capacity of a battery decreases drastically in just a year.

Capacity vs. cycles vs. resistance

Graph credit: Cadex

In recent years there has been development in solar-powered laptops. These computers do not offer robust processing power and are intended to network the developing world, but have found other niche uses.

Video card

This component translates binary code into a discernable image. These are responsible for various imaging demands of the system, including displaying 2D and 3D images and video, decoding video files, tuning broadcast TV signals, and synchronizing multiple monitors.

There are two types of video cards, dedicated video cards and integrated video cards, with the latter being more popular amongst laptop manufacturers due to its compact design, low power needs, simplicity, and cost. In this configuration, the video card is attached directly to the CPU or motherboard. However, it also shares RAM and power with these components which usually results in slower system performance. Dedicated video cards receive their own RAM, cooling components, and power allocation, and therefore are not optimal for portable computing, but are nonetheless used in some laptops.

Display

Notebook computers use flat-panel technology to create a vibrant and thin display panel. This technology significantly contributes to a laptop's compact design. These displays can be classified as:

• Liquid crystal displays (LCDs) are created by placing a liquid with crystalline properties between two electrically-conductive plates. The top plate has deposits of transparent electrodes and the back plate is a mirror. Electrical signals instruct segments of the liquid crystals to transmit or block light, and an image forms when light passing through the liquid crystals is reflected back to the viewer. This type of display is common in laptops.
• Electroluminescent displays (ELDs) rely on an electroluminescent material—placed between two conductors—to emit visible light in response to an electric current or field.
• Light-emitting diode (LED) displays use an arrangement of semiconductor light sources to simulate visualizations. The diode is akin to a p-n junction diode and electrons recombine with holes in the device to release photons. The color of the illumination is determined by the energy band gap of the semiconductor.
• Organic light-emitting diodes (OLED) operate in a manner similar to LED displays, but utilize an electroluminescent layer that is based on carbon.

Plasma displays are more vibrant and clear than other types of displays, but their power requirements make them inefficient for laptops. Research suggests plasma displays could eventually become a viable alternative.

Resolution is the value of pixels the display can represent. Common resolutions for screens that are 12 to 16 inches in size range from 1024 x 576 to 1440 x 900. Higher resolutions result in clearer imaging. Aspect ratio refers to the ratio of the display height and width. It is uncommon to find screen ratios outside of 16:10 and 16:9.

Expansion slots

These allow a user to customize the computing experience by adding various peripheral devices. These hardware plug-ins are commonly PCBs which add or enhance capabilities of the motherboard. Expansion slots have largely been usurped by USB ports.  

Media drives

Compact disc readers/writers are common on laptops, but are sometimes omitted to reduce size and weight. These optical drives create physical storage articles which can be accessed across devices. Data trends indicate that cloud-based data storage and streaming media are likely to eliminate removable media drives, much the way CD-based storage eliminated the floppy disk drive.

Hard drives

This memory provides comprehensive data storage for many media types. Laptop hard drive capacities can exceed 1 terabyte or more, but are typically less. Accessing data on a hard drive takes longer than data stored on RAM.

Inputs

Macbook trackpad; Lenovo Trackpoint (joystick); Powerbook trackball

The laptop user interfaces with the device via a keyboard and tactile directive instrument. Laptops most commonly utilize a trackpad, which is a capacitive, resistive, or conductance-based tactile sensor that translates finger movements into cursor position on the display. Laptops with a touchscreen display can do without a directive instrument. Less common cursor tracking methods utilize a joystick or trackball to interpret input, much akin to the trackpad. If the workspace allows, a mouse can easily be connected to the laptop via USB or Bluetooth.

Ports

This interconnect links the laptop with other computers or supporting hardware, such as USB 2.0 and 3.0 ports, peripheral video and audio ports, an Ethernet connection, serial ports, parallel ports, and Firewire.

Cooling equipment

Laptops generate an excessive amount of waste heat and this represents a burn and fire hazard. Heat piping systems move heat to the perimeter of the laptop. Internal fans circulate air flow within the device and heat sinks help exhaust this waste. Laptops constructed with a metallic case dissipate heat especially well.

Software

Since the CPU is algorithm-interpretive, software translates data between binary code and programming languages. Software constitutes all of the immaterial components which construct a computer.

• System software: is the immaterial architecture which initiates computer hardware and provides the underlying operation of the machine. This platform hosts other applications and software.
  • The operating system manages laptop resources, supervisory programs, boot loaders, maintenance programs, and window systems. Common operating systems include iOS®, Windows©, Android®, Linux, and UNIX.
  • The device driver is the software component that controls a specific piece of hardware. Each device needs at least one driver.
• Embedded software: this type of software also interfaces with the hardware of the machine, but represents a specific, single application for which the computer will be used. The hardware accompanying this application is optimized according to the task.  

• Applications: this type of software accesses and displays information so the user can complete a task. This includes processes such as document creation, access to various media, records storage, and gaming.

• Plug-ins: these extensions modify or enhance applications.

Types

Laptops and notebooks are most commonly used for general-purpose personal computing. Variants exist to fill niche roles in the portable computing marketplace.

Features

• Backlit keyboard: The keyboard illuminates to assist typing in dark locations.
• Bluetooth: The device uses Bluetooth technology to communicate with other electronics.   
• Biometric security: The device permits access via a biological identifier, such as a fingerprint scanner.
• EMI/RFI shielded: The laptop is insulated against electromagnetic and radio frequency interruptions.
• ENERGY STAR: This logo brandishes electronics and appliances which use 20-30% less energy than government guidelines.
• HDMI output: The laptop has a port to connect with high definition external monitors.
• Microphone: An audio capture mechanism facilitates voice chat and audio recording. Some laptops can operate via voice instruction.
• Optical drive: Data can be saved or accessed via CD, DVD, or Blu-ray storage disks.
• RAID: Data is a data storage method which saves information across several disk drives. This improves recall and reduces the chance for lost data, as data is saved according to distribution hierarchy, called RAID levels. RAID is an acronym for random array of independent disks.
• Webcam: An integrated webcam captures images and video.
• Wireless display: Compatible devices within the laptop's proximity can wirelessly simulate the display. 

Standards

Unequivocally, the Institute of Electronic and Electrical Engineers Standards Association (IEEE-SA) has been the leading standards body in regards to information technology and telecommunication. IEEE 1680 assesses all personal computers, including laptops. Other industrial standards manage a notebook computer's power supply, such as BS 62623 (notebook power consumption) and BS PD IEC/TS 62700 (DC power for laptops).

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