When your logo files get sent to you, you will find several types of files, some of which you probably can't open - don't move them to the trash! These are most likely your vector file versions. 

I create your logo in a vector-based program so that your logo can be represented as large as the moon if necessary - or even as small as a stamp - without losing any of its crispness, clarity, or quality. Unlike files created using pixels (little squares of colours, like in Photoshop) vector files never change because all the information is created using mathematical formulas and remains true, regardless of size. 

I use Adobe Illustrator and pay a hefty 'rental' fee for this software in order to use it. The .ai files I supply are Illustrator files, but I also include an .eps version. This is in order that other companies who may be using older, different, or free software can open your logo file and use it on their systems. These companies may not place a high priority on keeping their design software up to date with the latest new and expensive programmes, so it's important to include a file that doesn't hold back any branding opportunities for your business!

I have just sent a local print company an .eps file that they will send on to another company in order to create a 'stitch file' in order to be able to embroider the logo onto towels, shirts etc. 

Keep all your vector files somewhere safe!