Blockchain is a decentralized and distributed system with details of digital records of transactions. The digital based ledger records are often referred to as blocks. The blocks of individual records are linked together like a chain. Hence it is collectively referred to as a blockchain.
The blockchain was invented by Satoshi Nakamoto for public transaction of bitcoin cryptocurrency.
Blockchain contains information about data i.e. relevant information about transaction, hash which is a unique code for the block, previous blocks hash. The first block which does not have previous block’s hash is called Genesis block. This series of information inside a block helps in tracking the history and difficult to modify the blockchain records hence adds security.
How transactions are done in blockchain?
For a blockchain the decision of adding the transaction to the chain is done by consensus and not by a single administrator as incase of centralized system. The majority of computers connected in the network have to validate the transaction. Also data that is available on blockchain network cannot be deleted from all systems as everybody in the network holds copy of blockchain records.
Uses of blockchain?
In cryptocurrency like bitcoin blockchain technology is very useful. Bitcoin eliminates the need of middle layer of banks and helps in asset to asset transfer as it is without the conversion of currency values based on location.
In real estate, the use of blockchain eliminates the need of notary. The records of real estates buying and selling gets recorded in the blockchain.
In hospital management system blockchain is used to record patients relevant data for doctors to access.
Hashtag! well most of us know any word that begins with the pound(#) sign is a hashtag. Technically speaking, hashtag is a metadata i.e. information about data that is being posted on a social media or microblogging platforms.
Why is there a crazy trend to use a hashtag?
The microblogging platforms such as twitter limit the content length to 280 characters. So hashtag becomes a way of conveying the message using limited characters to the followers and audience, in general. The hashtag is a tagging that helps in referencing the content and acts as a keyword for content search and categorization of similar content. The hashtags can be informal combination of words to make it more catchy and make it viral and trending, that is the fun part of it 🙂
Companies and businesses have been using hashtags as a cool way of advertising and promoting their products and services. Most social media platforms such as instagram, twitter, facebook, linkedin, pinterest etc. provide hashtag support for posts and hashtag based search to catch attention of its audience and get views. So apart from searching for people, products, influencers, companies we can also search with keywords, phrases etc.
How hashtag came into existence ?
Hashtag was first proposed by Chris Messina in a tweet in the year 2007 on twitter platform. In the beginning, only twitter had the support for hashtag concept but gradually other social media platforms included hashtag looking at the emerging trend and usage by netizens.
This post in continuation to my earlier post which explains about Web cookie
There are types of web cookies namely
Session cookie: They are created during a session of user, stored in a temporary memory. They do not have any expiration date and are deleted immediately as soon as the browser is closed. The other popular names of session cookie are non-persistent cookie, transient cookie, in-memory cookie.
Persistent cookie: For this cookie, an expiration time is set. So, the cookie is deleted only at the expiration time and not deleted as soon as the browser is closed. They are used for maintaining session of the user. That is, once the user is logged into the website and if the user closes and reopens browser the cookie identifies if its a authorized user or not.
First party cookie: This cookie is set by the website and the cookie information can be used for analytics of page views, number of logged in users etc.
Third party cookie: Unlike first party cookie, this cookie is set by another website domain (not directly visited by user) whose plugins are used by the primary website.
Secure cookie: This is a cookie with encrypted data which can be used over an encrypted HTTPS connection. They are useful in e-commerce and banking websites where the safety and security of transactions in the topmost priority.
What is a web cookie?
Web cookie or browser cookie is a small piece of information which is send from website server to be stored in a user’s browser. The user may store it in its computer which is basically used to identify the computer. That is, maintain stateful information so the next time, user visits the website or on the next request it can send back, the cookie that can have some kind of information about the user that the server can make use of to make certain decisions. Other purposes could be for instance, track user’s browser activity or remember login details, track site’s user count etc.
Who invented it?
The term was coined by web browser programmer who invented cookie Lou Montulli in the year 1994 while building an e-commerce website.
Why do we see the cookie banner pop up?
The reason why we see the cookie banner popping up recently across most websites is because of legal concerns in Europe and some other countries, the GDPR(General Data Privacy Regulation) requires that the cookie banners be displayed on website to let the users know that cookies are being used by the website.
Where is a cookie useful?
Its used in session management to manage session of the user in ecommerce website. Its used for personalization like the settings that were set and saved by the user and as said earlier, also used for tracking to improve the user experience as they say it 😉
A Virtual Machine or a VM is a separate instance of operating system(OS) on a host physical computer in addition to host machine’s own OS, as if it were on a different computer or a guest. A host can emulate several guests, each of which can emulate different operating systems.
Host, guest and hypervisor
The computer that is running the virtual machine is called the host whereas the program that controls virtual machines is called a hypervisor. Virtual machines can be created through software known as virtualization software. Some of the popularly used virtualization softwares are Virtualbox and VMware.
What VMsoffer its users?
A VM can be easily created, modified and destroyed. We can also create and delete snapshot on a VM. A snapshot preserves the state and data of a virtual machine at a specific point in time. VM provides the flexibility to create and delete snapshots which takes a few minutes of time.
With the popularity of cloud services, cloud-based VMs use is in demand which can be accessed over an internet using a web browser. These VMs are created on a physical machine which is located at a different geographical location, which can be accessed remotely and shared by multiple users(not in parallel though) in a larger organization to make the process more agile.
One colleague at workplace had bought a brand new phone and forgotten his Type C charger at home and was asking for people around. If he was provided with one, he constantly checked the pin end to confirm the Type C. So, this is the latest USB in and around with the mobile devices we get to see. So, lets understand the USB and its evolution.
What was used before USB?
In the pre-USB era, communication between devices was done using communications ports namely parallel ports, serial ports, gaming ports etc.
What is a USB?
The USB stands for Universal Serial Bus is a standard connector used to connect peripherals to computer. Its is the most commonly used port and as the name says its quiet Universal. Its used to connect devices such as mice, cameras, printers, scanners, external hard drives, flash drives and even can do networking and also its used to charge devices such as mobile phones.
The 1st USB version was released in 1996 with release of USB 1.0. The versions are based on the speed of data transfer were
USB 1.0 which had a speed of 1.5 Megabits/sec.
USB 1.1 with a speed of 12 Megabits/sec,
USB 2.0 with a speed of 480 Megabits/sec
USB 3.0 with a speed of 5 Gigabits/sec
USB 3.1 with a speed of 10 Gigabits/sec
USB 3.2 with a speed of 20 Gigabits/sec
USB 4.0 with a speed of 40 Gigabits/sec
In addition to different speeds of USB there were different types of USB cables, connectors and ports it uses.
A typical USB cable has two ends with two different connectors, Type A at one end and Type B or Type C at the other end of the cable. Type A connector is the host connector. This can be plugged into computers Type A USB port
USB comes in various shapes and sizes: Standard, Mini, Micro. Each of these have types which are developed with the USB standards defined above.
Type A : is the original design for the USB standard with a flat and rectangular shape. Mostly used in host devices, including desktop computers, laptops, game, media players and so on.
Type B : plugs into peripheral device such as a printer, a phone, or an external hard drive.
Type C : is a USB with a rectangular shape with rounded corners. It supports USB 3.1 with the top speed of 10Gbps and has much higher power output of up to 20V and 5A.
A JSON object is enclosed inside curly brackets. Data is represented as key-value pairs separated by commas. Object data is represented inside curly brackets. Array data is represented inside square brackets.
Linting in software world means analyzing the developed source code for potential errors and warnings such as syntactical, logical (which might have got introduced without the knowledge of a developer) with the help of a program. The program is called as a lint or linter.
Why is linting important?
This mechanism of running lint ensures that the code is bug free and adheres coding guidelines of a particular language. This also helps in maintaining code quality reducing technical debt incurred.
JSLint is a static code analyser which checks if code complies JS coding rules. Its available on jslint.com. The CLI is also available. It was created by Douglas Crockford in the year 2002.
JSHint was created by Anton Kovalyov in the year 2011 and is a fork of Duoglas Crockford JSLint project. Anton thought that JSLint was “too opinionated and less configurable”. Both, online jshint.com and CLI versions are available for this.