| Word | Description |
| Z-Buffering (or Hidden Surface Removal) | This tracks the depth of each triangle in a 3D graphics representation, from the perspective of the viewer, to ensure that objects behind other objects in a scene don’t appear until the viewer has them in his or her line of sight. This is why you can’t see through walls to what lies behind, but why you can play multiplayer Quake and have people at many different areas in a level. |
| Zebibyte | A zebibyte is a unit of data storage that equals 2 to the 70th power, or 1,180,591,620,717,411,303,424 bytes. While a zettabyte can be estimated as 10^21 or 1,000,000,000,000,000,000,000 bytes, a zebibyte is exactly 1,180,591,620,717,411,303,424 bytes. This is to avoid the ambiguity associated with the size of zettabytes. A zebibyte is 1,024 exbibytes and precedes the yobibyte unit of measurement. |
| Zero Administration Kit (ZAK) | A software kit from Microsoft originally for Windows NT that can prevent various user actions, such as installing software or changing desktop configurations. |
| Zero Day Exploit | A zero day exploit is a malicious computer attack that takes advantage of a security hole before the vulnerability is known. This means the security issue is made known the same day as the computer attack is released. In other words, the software developer has zero days to prepare for the security breach and must work as quickly as possible to develop a patch or update that fixes the problem. Zero day exploits may involve viruses, trojan horses, worms or other malicious code that can be run within a software program. While most programs do not allow unauthorized code to be executed, hackers can sometimes create files that will cause a program to perform functions unintended by the developer. Programs like Web browsers and media players are often targeted by hackers because they can receive files from the Internet and have access to system functions. While most zero day exploits may not cause serious damage to your system, some may be able to corrupt or delete files. Because the security hole is made known the same day the attack is released, zero day exploits are difficult to prevent, even if you have antivirus software installed on your computer. Therefore, it is always good to keep a backup of your data in a safe place so that no hacker attack can cause you to lose your data. |
| Zettabyte | Unit of storage. Often abbreviated to ZB. 1 zettabyte (ZB) = 2 to the seventieth power (270) bytes = 1,180,591,620,717,411,303,424 bytes = 1024 exabytes = 250 megabytes. 1024 zettabytes = 1 yottabyte. |
| ZIP | 1. To zip a file is to compress a file (or folder) using lossless compression. Correspondingly, to unzip a file is to decompress the file. 2. Zone Improvement Plan. A US postal service code used to facilitate the delivery of mail to the correct location. Where each delivery area is assigned a different code. Many other countries use similar schemes (details are obviously very different) using a code to indicate the area that post needs to be delivered. Elsewhere these are typically referred to as postcodes. A zip code was originally a five digit number, where the first three digits indicated the state or area within a state and the last two digits a specific postal delivery zone. This was later expanded by four digits to become known as ZIP + 4, with the first two additional digits indicating a postal sector and the last two a postal segment. Normally abbreviated to ZIP, ZIP +4 (see above) or ZIP code. 3. A fastening device. Known in British-English as a zip but in US-English as a zipper. |
| zipped files | Zipped files are files that are compressed and must be "unzipped" to be read. Zipped files download faster because they are smaller than an uncompressed equivalent. |
| Zmodem | This protocol has many error-correcting properties. It can detect if a bad block (of 1,024 bytes) has come through and ask to have it resent. If the transfer gets interrupted for any reason, it can resume from where it left off. It is slightly slower than Ymodem-G, but is much more reliable. |
| Zone | A sub-tree of a DNS domain. |
| Zone File | A zone file is stored on a name server and provides information about one or more domain names. Each zone file contains a list of DNS records with mappings between domain names and IP addresses. These records define the IP address of a domain name, the reverse lookup of an IP to other domains, and contain DNS and mail server information. Because zone files are plain text files, they can be edited quickly and easily. However, this also means that if unauthorized users gain access to zone files, the files can be easily modified. This could cause websites to not respond, or worse yet, redirect to the wrong Web server. For this reason, it is important to keep the zone files on a highly secured server and always have a recent backup of zone files on another machine. |
| Zone of Authority (Zone) | A term having to do with DNS. Each top-level domain name, such as Geek.com, is considered a zone, where subdomains such as server1.geek.com or www.geek.com are managed by their own DNS servers. Geek.com’s Zone of Authority is all the subdomains under Geek.com. |
| Zone Transfer | he act of replicating a zone file from one DNS server to another. |
| zoom | The act of enlarging a portion of an onscreen image for fine detail work; most graphics programs have this capability. |
