A method in a host computing system for providing access via a remote Web client to applications (123 a; 123b) on the host computing system, the Web client executing on a client device having a display device, the method comprising: providing a uniform resource identifier that identifies an application executing on the host computing system; receiving a request to access the application, the request received from the remote Web client and based on the uniform resource identifier; causing the remote Web client to display a graphical user interface of the application; receiving from the remote Web client indications of inputs made by the user with respect to the displayed graphical user interface; and facilitating user interaction with the application on the host computing system, wherein the host computing system includes multiple virtual machines (131a-n) that each host one or more applications, wherein each of the multiple virtual machines provides remote access to the one or more applications to a distinct Web client, the method characterized by the facilitating user interaction with the application on the host computing system comprising: storing image data comprising an output graphical user interface generated by the application in a virtualized display buffer that emulates a hardware frame buffer in the host computing system; transmitting the image data from the virtualized display buffer in the host computing system to the remote Web client; causing the remote Web client to display the graphical user interface of the application received from the virtualized display buffer; in response to receiving the indications of user inputs, (200;202) forwarding the indications of user inputs to the application; determining modified image data blocks by performing a block-by-block comparison between the graphical user interface of the application and the received client indications of inputs made by the user with respect to the displayed graphical user interface; wherein a block size in the block-by-block comparison is based on a network latency and/or a scope modification and/or an amount of modification; and transmitting to the remote Web client the determined modified image data blocks for display by the remote Web client. providing a uniform resource identifier that identifies an application executing on the host computing system; receiving a request to access the application, the request received from the remote Web client and based on the uniform resource identifier; causing the remote Web client to display a graphical user interface of the application; receiving from the remote Web client indications of inputs made by the user with respect to the displayed graphical user interface; and facilitating user interaction with the application on the host computing system, wherein the host computing system includes multiple virtual machines (131a-n) that each host one or more applications, wherein each of the multiple virtual machines provides remote access to the one or more applications to a distinct Web client, the method characterized by the facilitating user interaction with the application on the host computing system comprising: storing image data comprising an output graphical user interface generated by the application in a virtualized display buffer that emulates a hardware frame buffer in the host computing system; transmitting the image data from the virtualized display buffer in the host computing system to the remote Web client; causing the remote Web client to display the graphical user interface of the application received from the virtualized display buffer; in response to receiving the indications of user inputs, (200;202) forwarding the indications of user inputs to the application; determining modified image data blocks by performing a block-by-block comparison between the graphical user interface of the application and the received client indications of inputs made by the user with respect to the displayed graphical user interface; wherein a block size in the block-by-block comparison is based on a network latency and/or a scope modification and/or an amount of modification; and transmitting to the remote Web client the determined modified image data blocks for display by the remote Web client. storing image data comprising an output graphical user interface generated by the application in a virtualized display buffer that emulates a hardware frame buffer in the host computing system; transmitting the image data from the virtualized display buffer in the host computing system to the remote Web client; causing the remote Web client to display the graphical user interface of the application received from the virtualized display buffer; in response to receiving the indications of user inputs, (200;202) forwarding the indications of user inputs to the application; determining modified image data blocks by performing a block-by-block comparison between the graphical user interface of the application and the received client indications of inputs made by the user with respect to the displayed graphical user interface; wherein a block size in the block-by-block comparison is based on a network latency and/or a scope modification and/or an amount of modification; and transmitting to the remote Web client the determined modified image data blocks for display by the remote Web client.