This is a dataset consisting of a training set of 60,000 examples and a test set of 10000 examples. Each example is a 28x28 grayscale image, associated with a label from 10 classes

Each image is 28 pixels in height and 28 pixels in width, for a total of 784 pixels in total. Each pixel has a single pixel-value associated with it, indicating the lightness or darkness of that pixel, with higher numbers meaning darker. This pixel-value is an integer between 0 and 255. The training and test data sets have 785 columns. The first column consists of the class labels (see above), and represents the article of clothing. The rest of the columns contain the pixel-values of the associated image.

To locate a pixel on the image, suppose that we have decomposed x as x = i * 28 + j, where i and j are integers between 0 and 27. The pixel is located on row i and column j of a 28 x 28 matrix.

Labels
Each training and test example is assigned to one of the following labels:

0 T-shirt/top
1 Trouser
2 Pullover
3 Dress
4 Coat
5 Sandal
6 Shirt
7 Sneaker
8 Bag
9 Ankle boot

TL;DR

Each row is a separate image
Column 1 is the class label.
Remaining columns are pixel numbers (784 total).
Each value is the darkness of the pixel (1 to 255)