SSL certificates are used to secure data transfer with websites. A website uses SSL if the URL begins with https or has the security lock symbol.
Code signing is used to sign software. This signature ensures the validity of the software.
Personal signatures are used to sign emails (S/MIME) or word documents.
Document signatures are used to sign Adobe PDF files and ensure their integrity against manipulation
What is SSL?
SSL is the abbreviation for Secure Sockets Layer and means that the connection and all data sent to a server system is encrypted. This encryption channel is established before there is data actively sent to the website, to ensure that the data can't be copied or manipulated, even when you transmit it over WiFi. There is more than just SSL certificates for websites, there are also certificates for documents (PDF, Word), Emails (S/MIME) or software.
What is important for SSL?
SSL certificates can be issued with different encryption depths. Common values are 128, 256, 512, 1024 and 2048 bits. Having more bit depth in your SSL certificate means that it's more unlikely that somebody will be able to break the encryption. For smaller or private websites bitrates of 128 are suitable. Bigger websites, online shops and websites dealing with payment data should have at least 256 bits in encryption depth.
The fitting product
To find a SSL product that fits your needs always depends on the field you'll be using it. Do you want to sign PDF files? Do you want to sign Word documents? Do you want to sign binary data? Do you want to encrypt your website with https and offer a secure channel of communication with your website visitors? Finding the correct type of certificate isn't hard, but what SSL certificate should you use for your website?
For smaller and private websites the cheapest SSL certificate will be enough. Bigger internet shops dealing with more secure data should tend to more expensive ones.