Bandwidth throttling is quite synonymous with any other web hosting terminology. While getting your site hosted, there are some terms and conditions about bandwidth usage that is permissible per month. Technically, this information should be clearly specified in your agreements with the hosting company. This is very important if you expect heavy traffic or data exchange during specific days or time of the year.
The hosting companies use a throttling device that limits the amount of data that your site transmits or accepts within a specified time period. This is to ensure that other sites are not affected if your site begins to use too many resources of server or network. Bandwidth throttling ensures quality service and prevents network congestion or server crashes.
When server reaches the bandwidth limit, a bandwidth throttling device can block the user requests and moves the users in a queue. Depending on your agreement, your site may go offline to accommodate other sites that are hosted on same server. However, if this happens frequently, it may adversely impact your business.
Bandwidth throttling blocks reading requests first and user can continue writing if it reaches the limit for example, while submitting a query form. So you need to evaluate your business requirements carefully, and then enter bandwidth related agreement with your host.
Sometimes, a host can use excessive throttling and target for upgraded hosting plans. When your site is offline, you are tempted to upgrade your hosting pack. Ensure that your host is genuine in bandwidth claims; else, look out for some other host.