 Welcome to the course on computer programming. In this session we will see how best can we use our computer. So, let us turn on that is switch on our computer. Some people will also call as booting a computer. Please note that there will be a similar setup at your end, but not an exact one. The setup will vary depending on the model of your monitor, on your printer, the CPU etc. We will first switch on the main switch which connects to the spike guard. A spike guard is providing power to the monitor CPU. We will now turn on our monitor. We can see this blue light. We now press the round button of a CPU. We can feel the vibration on the CPU cabinet and can also see some text on the monitor. The computer will start now. Now, imagine that there are four families staying in a building. Every family has a key to access their respective houses. A family cannot enter other family's house with his or her own house key. Similarly, there are four users of this computer, each having a key that is a password to access it. Since we do not like to share our house key with anyone else, similarly we should also make a practice of not sharing the password with anyone else nor even writing it down anywhere. Now, I will enter the password of my computer and press enter. This will now give me access to my computer. As you can see, I have now got access and this is my home. This screen is known as the desktop. Desktop is nothing but the screen that is visible when the computer starts. A desktop screen can be imagined as a hall or a living room of a house. Now, let us move on to create some folders. But before going ahead, let us go to one part of our room. We can see this table. This is the electricity file having some record of bills of many years. This is the mathematics file containing some interesting material related to mathematics, some calculus, some formulas, etcetera. Similarly, I see some other files too on this table. Since they are scattered all over, let me just stack them up. Now, suppose if after a few days somebody would ask me for my electricity bill of 2012, I would have to search through all these files. These files will increase day by day and at one point it would be impossible for me to locate any material which I may need. Now, let us go to other part of our room. This is indeed quite neat and tidy. These cabinets can be imagined as a folder. Every folder is well named and contains respective files. This electricity folder contains files related to electricity only. This folder contains file pertaining to science only and so on. As we all expect our houses to be neat and tidy, similarly we should also maintain this for our computers too and organize our folders, our files in a methodical way. Now, let us go back to our computer and get started. Let us now create a folder. Click the right button on the mouse, we can also say right click your mouse. Move your mouse to the text create new folder. This text untitled folder has got highlighted. Now, we will write the name of this folder called subjects and we will press enter. As you can see the folder called subjects has got created on a desktop. This folder is highlighted hence we will move our mouse away from this folder anywhere on the desktop and left click the button. Now, we will double click the subjects folder to go inside the subjects folder. Double click is nothing but clicking of the left click button twice but at a faster rate. Double click on subjects, we can now see the subjects folder which is empty. We will create another folder, right click create new folder. We will name it as mathematics, we will now press enter. Let us now create another folder called science. In this way we can create folders inside another folder. A folder can also be termed as directories. Now, let us rename the folder to history, right click the science folder and click rename. The science text has got highlighted, we will now write history and press enter. As you can see the history folder now appears before the mathematics folder. This is because the alphabetical order is followed while naming files and directories. Now, let us close this folder, we will go to the top left of the screen where we can see this cross sign and we will click on it. We are now back to our desktop. As a good practice we generally do not keep all the furniture in the living room. We distribute it to other rooms like kitchen, bedroom, study room etc. Similarly, we should not have everything on this desktop too. We will now move this subjects folder by clicking the left click of a button dragging it and dropping it below this folder. We will now go to our home folder. This entire pane is called the left pane. We will click on our home folder where we can see that there are folders which are already existed with some files. We will now close this home folder. Let us browse some applications on this computer. We will click the dash home button. As you can see something is already written over here, press the back space of your button. We can see the recent applications which we have used. We will write g edit and press enter. The g edit window has appeared over here. We now need to save this file. Let us click file, save as. We will browse through the appropriate folder which is desktop, subjects, mathematics. Over here we need to write the title of the file. Say we want to create a file having some formulas or let us term it as calculus. Txt is nothing but the extension of the text file. We will now click on the save file button. Let us now write something into this file. So, hello, I am Feroza Ibarra taking this lecture on computers. Once we have modified this file, you will see that there is a asterisk sign which appears. We now need to click save to save the file. We can do various operations like undo, cut, copy, paste and many others using g edit and other applications too. We will now close this file. Now let us browse some existing files on a computer. Let us double click on CS101.1x, IIT Bombayx, July 2015. This folder contains some material related to a course. We can see that there are some PDF files, a programming file and an image file. Let us open a PDF file by double clicking on it. The PDF file has opened up. We can browse the PDF file by scrolling up and down using the mouse or using the up and down arrow keys of a keyboard. Now, let us close this file and view the image in a folder. Program underscore image1 is a PNG file. Double click on it, our image has opened up. We can see that there is a table, some part v, step 2, step 1 etc. Let us close this. We will now browse through a programming code. This is the .cpp file. Right click on this file. We can see that we can open the file using the text editor or if we want to open the file using code blocks, we can scroll down to open width and select code blocks. Let us select the text editor. Text editor is the default application for opening the program on my computer. We can browse through this code. We can edit it, say cout, hello world and we can save this. We can now close this file. We can change the way the folder looks. The current view is of the icons. We can make it list, we can make it compact. Let us click on list and see what happens. The files are used as a list. We can see the type of the document. This is the PDF, this is the C++ source code and this is the PNG and then it was modified. Let us revert back to our original format that is the icon format. Now consider that you want to mail this folder to a friend of yours. Mailing each and every file individually will become quite tedious. An option is to compress all these files into one file. So let us see how can we do that. We will close it so that we can see our desktop. We will right click on this folder and we will click compress. We can see this window. The type of file which will be compressed is tar dot gz. We can change it to zip tar. So let us select zip and we will name it as contents cs11.1x contents and click the create button. As you can see the cs101 dot zip folder has appeared over here. Now this file can be sent to your friend using email. Let us right click on this folder and see the properties. It is a zip file having size 2.4 MB. The process of uncompressing the file is similar to the process of compressing. For example if you want to uncompress this file, right click on this file and click extract here. Currently we are not extracting this because the folder is already present on our desktop. Whenever we go outside we generally switch off the lights, fans, locker house etc. Similarly we should always lock our computer if it is unattended or switch it off when we are not going to use it for a very long time. So let us shut our system down. Click this power button and click shutdown. We conclude this lecture and I hope that the participants who are new to computers will benefit from this lecture. Thank you.