Equipment colocation (aka co-location) is when an organization pays to rent space in another organization's networked facility. It is a common practice for web hosting, as it allows a company to put their equipment into a controlled, reliable, networked environment without having to build or buy their own data center. If your company or other organization needs to be on the Web, colocation may be a good option – especially if you have special requirements such as non-standard equipment.

There are many reasons why colocation may make sense for you. One may be cost – by renting space in another company's data center, you can simply move your equipment into that location and “plug it in” - the other company takes care of keeping it cooled and supplying it with power and internet access. One scenario in which this really makes sense is if your organization has a server already running on the premises, but is having problems keeping it online, and keeping it secure. By colocating that server to another company's data center, all you need to do is unplug the server, drive it over to the new location and plug it in!

Another common reason for equipment co-location is to allow an organization to spread its online resources around geographically. This may be useful in terms of performance – by allowing equipment to help deal with traffic coming from that geographical area. It also can offer some redundancy in case of natural disaster. For example, you can be sure that large online companies like google do not have “all their eggs in one basket” but instead have data centers scattered all over the globe. Of course building facilities all over the place is not feasible for a lot of organizations – but by renting colocation space in a few data centers scattered around, your company could possible gain some benefit over concentrating everything in one location.

Contextual advertising is a form of targeted advertising for advertisements appearing on websites or other media, such as content displayed in mobile browsers. The advertisements themselves are selected and served by automated systems based on the content displayed to the user.

Cost per impression, often abbreviated to CPI or CPM for Cost per thousand impressions, is a phrase often used in online advertising and marketing related to web traffic. It is used for measuring the worth and cost of a specific e-marketing campaign. This technique is applied with web banners, text links, e-mail spam, and opt-in e-mail advertising, although opt-in e-mail advertising is more commonly charged on a cost per action (CPA) basis although sometimes CPM is used.

An online advertisement impression is a single appearance of an advertisement on a web page. Each time an advertisement loads onto a user's screen, the ad server may count that loading as one impression. However, the ad server may be programmed to exclude from the count certain nonqualifying activity such as a reload, internal user actions, and other events that the advertiser and ad serving company agreed to not count. For online advertising, the numbers of views can be a lot more precise. When a user requests a web page, the originating server creates a log entry. Also, a third party tracker can be placed in the web page to verify how many accesses that page had. There are other advertising pricing structures, which are generally referred to as Cost Per Action (CPA) :

* CPC - Cost per click Through
* CPL - Cost per lead (lead usually meaning a free registration)
* CPS - Cost per sale
* dCPM - Dynamic CPM

CPI and/or Flat rate advertising deals are sometimes preferred by the publisher/webmaster because they will receive a more consistent fee proportional to the amount of traffic.

Today, it is very common for large publishers to charge for most of their advertising inventory on a CPM or CPT basis. A related term, effective cost per mille (CPM), is used to measure the effectiveness of advertising inventory sold (by the publisher) via a CPC, CPA, or CPT basis.

This type of advertising arrangement closely resembles television and print advertising methods for speculating the cost of an advertisement. Often, industry agreed approximates are used. With television, the Nielsen Ratings are used; print is based on the circulation a publication has.