When your logo is designed by a logo designer, he will give you some digital files. You may be confused as to why there are so many files and not just one which has your logo. Here is a brief explanation of what those files are:
PNG stands for Portable Network Graphic and is used solely for digital purposes. This file can also be printed but it is recommended to do so. It is also created such that, if you expand or minimize the image, it won't lose its quality. It is used for websites, blogs, your company's social media profile photo, cover photos and such. This file usually comes in a colored version and a black and white version as well.
SVG stands for Scalable Vector Graphic and is used mostly for printing purposes. It can also be expanded or minimized and it won't lose its quality. It is a smaller size than PNG and JPG files and can be edited using software like Adobe Illustrator. It can also be used in your blogs and websites and such but some websites do not support SVGs so instead, it is mostly used for printing on business cards, clothes, labels, posters and more. In case, you wish to rebrand your logos after a few years, you can send this file to a logo designer and he will easily make some small changes and alterations to your logo design. These will be delivered to you with a colored background and also a transparent background.
EPS stands for Encapsulated PostScript and are usually called "master files" and "working files". These can be used for three purposes: printing, editing and posting online on social media platforms and such. These can also be edited using software like Adobe Photoshop, Adobe Illustrator and more. These are usually hard to access without Adobe software. They are also very scalable and can be expanded as big as a billboard and as small as a business card. This file is delivered to you with a colored and transparent background.
PDF stands for Portable Document Format. These are easier to share because it remains the same on any device. You can use these files for printing on business cards, shirts and more. It can easily be accessed using Adobe Acrobat Reader which is mostly present in everyone's PCs. You can edit this file using Adobe Photoshop or Adobe Illustrator.
Summarizing the above, we can say that if you want to use your logo design for digital purposes, you should use the PNG files. If you want to send your logo design for printing, use SVG files; if these files are not accepted by the printer, your second option should be the EPS files and then the PDF files. If you want to make some changes to your logo design, either of the SVG or the EPS files can be used.