What exactly exposure means..

When we talk about exposure,we refer to how long the shutter of the camera is let open.The speed with which shutter behaves(i.e opens or closes),determines for how long the digital sensor in a camera is exposed.
This is generally determined by the shutter speed in the camera(which can be accessed in camera's with manual settings)
shutter speeds vary broadly b/w :- 1/4000 of a second to 30 seconds.
1/4000 means that the shutter speed is very fast and camera's digital sensor is exposed for only 1/4000 seconds.
30 indicates very slow shutter speed,in which the digital sensor is exposed to light for 30 seconds.
We normally give 30 sec.exposures,in case light conditions are dim and we require more detailing.(as in case the pictures down the line)
For shooting fast moving objects,we prefer to go for smaller exposures(1/2000 , 1/4000 , etc..)

Macro Mode

A couple'f photographs down the line , elucidate the principle of using Macro Mode.
Now,what exactly macro means , i'll state it as- A setting,that changes the focus of the camera so it can focus on very close objects. The macro setting is for photographing objects within a few inches or feet away.Macro-setting may work upto 1 cm in some cams.It gives a crisp detailing of an object under focus , while the rest of the background remains out'f focus , thereby rendering it faded.

Macro setting can be used to improve the ability to see small details, similar to using a magnifying glass.however,care must be taken,regarding the lighting conditions.proper exposure,needs to be adjusted,and also,the shutter speed ought to be accordingly adjusted,so as shots stays steady enough (specially,when shooting,free hand).
What to be kept in mind??
Identify,object's foreground as well as it's background.
Choose object's distance aptly,so as it is correctly focused.

A depiction for using Macro Settings

Sorting Main Differences between Analog(with Film) and Digital Photography

What is an Analog Camera??
In an Analog Camera,the external structure may more or less seem similar,but it's Photo capturing principle is primarily based on storing clicked pictures on a film.
A picture taken on film is composed of numerous, tiny, light-sensitive silver-halide crystals that are chemically-processed in order for the image to be made.
Now,what is a Digital Camera??
In this, the photo capturing principle is entirely differnt from that of an analog camera.
the picture information here,is stored on a 'Digital-Sensor'.
This sensor is Semiconductor diode,which converts incoming light into various pixel intensity values.
There are mainly two types of sensors available in market at the moment..these are-"CCD type"
and "CMOS type".
CCD is a Charged Coupled Device,whereas CMOS is a Complimentary Metal Oxide Semiconductor.
A picture recorded digitally is made up of numerous, tiny, light-sensitive pixels that form an image that can be viewed on a computer monitor or the viewing screen of some digital cameras.
Most digital cameras function in much the same way as a traditional camera that uses film to record images, except that in place of the film, images are captured and preserved in the camera’s digital memory, which may be built-in or which may be on a removable memory card.
The number of images the camera’s memory or memory card holds varies dependent on image quality and type (i.e. black and white, color or sepia-toned), the quality of the camera and the memory capacity. New technology for digital imaging is emerging rapidly and multi mega-pixel image storage capacity is quickly becoming affordable with each new generation of cameras.

A great advantage of many digital cameras that have an LCD viewfinder (a mini monitor screen) is the ability to review images stored in the camera's memory at any time and to delete any unwanted images at the photographer's convenience, thus freeing up storage space for new images, while retaining only the best images for later retrieval and downloading.
Digital imagery is the fastest-growing area of photography, with changes and improvements in products and techniques occurring almost daily.

What does Aperture and Depth of Field for any camera imply?

When we refer to the “aperture” of a lens, we are speaking on an iris, similar to that in the
pupil of an eye, that opens or closes, allowing light to enter and strike the optic nerve,
sending impulses to the brain. A lens aperture works much the same, except it will allow as
much light to enter as we tell it to allow. While our brains can automatically compensate for
light or dark (a human with good vision is capable of seeing light as dim as a trillionth of a
watt), if our ISO Settings go a bit higher, the result will be an overexposure that the camera cannot compensate for.

A camera’s aperture is composed of thin metal blades that, when the shutter is actuated, move together in less than a blink of an eye to form a circle corresponding to the
chosen f-stop(focal number). After the chosen shutter speed has expired, and the shutter has been closed, they move
back to their zero position to wait for the next actuation. .