Changing the size of images in Photoshop has many advantages over other photo editing software like Paint, Snag It, etc. You can adjust image sizes using preset templates or customize them as desired.

Altering the dimensions of images in Photoshop can affect the quality of the original image. Shrinking images can reduce file size, while enlarging them can result in blurred and pixelated images. Therefore, it's important to set image parameters with an appropriate ratio to produce the highest quality images. Let's proceed.
Step 1: Open the image you want to resize. Then go to Menu Image => Image Size… or press the Alt + Ctrl + I shortcut keys.

Step 2: After opening Image Size, a new dialog box appears. Adjust the settings as needed.
Pixel Dimensions Section: Displays image dimensions alongside.
Width: Adjusts the length of the image.
Height: Adjusts the height of the image.
Document Size Section: Adjusts the overall size of the image. In addition to Width and Height, there's also the option for Resolution. Modifying parameters in the Document Size section can indirectly affect Pixel Dimensions and vice versa.

- Scale Styles: This option is used to adjust the image's scale.
- Constrain Proportions: Helps you lock the aspect ratio of the image horizontally and vertically. This prevents your image from becoming distorted due to improper scaling. If you don't like the default image ratio, you can turn off this option.
- Resample Image: Allows customization of image quality after resizing. When enabling this option, we can only change the image size in the Document Size section as this option affects all pixels in a particular image.

Step 3: After adjusting the parameters, press the OK button and see the results.

Image before resizing with dimensions of 500x632 pixels, file size 925 Kb.

Image after resizing to 300x379 pixels with file size 333.1 Kb.
For images resized in Photoshop, you can compress file size by reducing image resolution for easy sharing with friends or using as profile pictures on Facebook. However, enlarging small images may result in pixelation or blurriness, so this feature is best suited for downsizing. Wishing you success in achieving your desired images for your intended purpose!