diff --git a/doc/RTD/source/Task/adding_your_own.rst b/doc/RTD/source/Task/adding_your_own.rst
new file mode 100644
index 0000000000000000000000000000000000000000..6f6b37899b505a5bbf6a09d8757232e0b547a081
--- /dev/null
+++ b/doc/RTD/source/Task/adding_your_own.rst
@@ -0,0 +1,262 @@
+.. Task
+ Loic Hausammann 17th July 2018
+
+.. _task_adding_your_own:
+.. highlight:: c
+
+Adding a Task
+=============
+
+First you will need to understand the dependencies between tasks
+using the file ``dependency_graph.dot`` generated by swift at the beginning of any simulation and then decide where it will fit (see :ref:`task`).
+
+For the next paragraphs, let's assume that we want to implement the existing task ``cooling``.
+
+Adding it to the Task List
+--------------------------
+First you will need to add it to the task list situated in ``task.h`` and ``task.c``.
+
+In ``task.h``, you need to provide an additional entry to the enum ``task_types`` (e.g. ``task_type_cooling``).
+The last entry ``task_type_count`` should always stay at the end as it is a counter of the number of elements.
+For example::
+
+ enum task_types {
+ task_type_none = 0,
+ task_type_sort,
+ task_type_self,
+ task_type_pair,
+ task_type_sub_self,
+ task_type_sub_pair,
+ task_type_ghost_in,
+ task_type_ghost,
+ task_type_ghost_out,
+ task_type_extra_ghost,
+ task_type_drift_part,
+ task_type_end_force,
+ task_type_kick1,
+ task_type_kick2,
+ task_type_timestep,
+ task_type_send,
+ task_type_recv,
+ task_type_cooling,
+ task_type_count
+ } __attribute__((packed));
+
+
+In ``task.c``, you will find an array containing the name of each task and need to add your own (e.g. ``cooling``).
+Be careful with the order that should be the same than in the previous list.
+For example::
+
+ /* Task type names. */
+ const char *taskID_names[task_type_count] = {
+ "none", "sort", "self", "pair", "sub_self",
+ "sub_pair", "ghost_in", "ghost", "ghost_out",
+ "extra_ghost", "drift_part", "end_force", "kick1",
+ "kick2", "timestep", "send", "recv",
+ "cooling"};
+
+
+Adding it to the Cells
+----------------------
+
+Each cell contains a list to its tasks and therefore you need to provide a link for it.
+
+In ``cell.h``, add a pointer to a task in the structure.
+In order to stay clean, please put the new task in the same group than the other tasks.
+For example::
+
+ struct cell {
+ /* Lot of stuff before. */
+
+ /*! Task for the cooling */
+ struct task *cooling;
+
+ /*! The second kick task */
+ struct task *kick2;
+
+ /* Lot of stuff after */
+ }
+
+
+Adding a new Timer
+------------------
+
+As SWIFT is HPC oriented, any new task need to be optimized.
+It cannot be done without timing the function.
+
+In ``timers.h``, you will find an enum that contains all the tasks.
+You will need to add yours inside it.
+For example::
+
+ enum {
+ timer_none = 0,
+ timer_prepare,
+ timer_init,
+ timer_drift_part,
+ timer_drift_gpart,
+ timer_kick1,
+ timer_kick2,
+ timer_timestep,
+ timer_endforce,
+ timer_dosort,
+ timer_doself_density,
+ timer_doself_gradient,
+ timer_doself_force,
+ timer_dopair_density,
+ timer_dopair_gradient,
+ timer_dopair_force,
+ timer_dosub_self_density,
+ timer_dosub_self_gradient,
+ timer_dosub_self_force,
+ timer_dosub_pair_density,
+ timer_dosub_pair_gradient,
+ timer_dosub_pair_force,
+ timer_doself_subset,
+ timer_dopair_subset,
+ timer_dopair_subset_naive,
+ timer_dosub_subset,
+ timer_do_ghost,
+ timer_do_extra_ghost,
+ timer_dorecv_part,
+ timer_do_cooling,
+ timer_gettask,
+ timer_qget,
+ timer_qsteal,
+ timer_locktree,
+ timer_runners,
+ timer_step,
+ timer_cooling,
+ timer_count,
+ };
+
+As for ``task.h``,
+you will need to give a name to your timer in ``timers.c``::
+
+ const char* timers_names[timer_count] = {
+ "none",
+ "prepare",
+ "init",
+ "drift_part",
+ "kick1",
+ "kick2",
+ "timestep",
+ "endforce",
+ "dosort",
+ "doself_density",
+ "doself_gradient",
+ "doself_force",
+ "dopair_density",
+ "dopair_gradient",
+ "dopair_force",
+ "dosub_self_density",
+ "dosub_self_gradient",
+ "dosub_self_force",
+ "dosub_pair_density",
+ "dosub_pair_gradient",
+ "dosub_pair_force",
+ "doself_subset",
+ "dopair_subset",
+ "dopair_subset_naive",
+ "dosub_subset",
+ "do_ghost",
+ "do_extra_ghost",
+ "dorecv_part",
+ "gettask",
+ "qget",
+ "qsteal",
+ "locktree",
+ "runners",
+ "step",
+ "cooling",
+ };
+
+
+You can now easily time
+your functions by using::
+
+ TIMER_TIC;
+ /* Your complicated functions */
+ if (timer) TIMER_TOC(timer_cooling);
+
+
+Adding your Task to the System
+------------------------------
+
+Now the tricky part happens.
+SWIFT is able to deal automatically with the conflicts between tasks, but unfortunately cannot understand the dependencies.
+
+To implement your new task in the task system, you will need to modify a few functions in ``engine.c``.
+
+First, you will need to add mainly two functions: ``scheduler_addtask`` and ``scheduler_addunlocks`` in the ``engine_make_hierarchical_tasks_*`` functions (depending on the type of task you implement, you will need to write it to a different function).
+
+In ``engine_make_hierarchical_tasks_hydro``,
+we add the task through the following call::
+
+ /* Add the cooling task. */
+ c->cooling =
+ scheduler_addtask(s, task_type_cooling, task_subtype_none, 0,
+ 0, c, NULL);
+
+As the ``cooling`` cannot be done before the end of the force computation
+and the second kick cannot be done before the cooling::
+
+ scheduler_addunlock(s, c->super->end_force, c->cooling);
+ scheduler_addunlock(s, c->cooling, c->super->kick2);
+
+
+The next step is to activate your task
+in ``engine_marktasks_mapper``::
+
+ else if (t->type == task_type_cooling || t->type == task_type_sourceterms) {
+ if (cell_is_active_hydro(t->ci, e)) scheduler_activate(s, t);
+ }
+
+Then you will need to update the estimate for the number of tasks in ``engine_estimate_nr_tasks`` by modifying ``n1`` or ``n2``.
+
+Initially, the engine will need to skip the task that updates the particles.
+It is the case for the cooling, therefore you will need to add it in ``engine_skip_force_and_kick``.
+
+Implementing your Task
+----------------------
+
+The last part is situated in ``runner.c``.
+
+You will need to implement a function ``runner_do_cooling``
+(do not forget to time it)::
+
+ void runner_do_cooling(struct runner *r, struct cell *c, int timer) {
+
+ TIMER_TIC;
+
+ /* Now you can check if something is required at this time step.
+ * You may want to use a different cell_is_active function depending
+ * on your task
+ */
+ if (!cell_is_active_hydro(c, e)) return;
+
+ /* Recurse? */
+ if (c->split) {
+ for (int k = 0; k < 8; k++)
+ if (c->progeny[k] != NULL) runner_do_cooling(r, c->progeny[k], 0);
+ } else {
+ /* Implement your cooling here */
+ }
+
+ if (timer) TIMER_TOC(timer_do_cooling);
+ }
+
+
+
+and add a call to this function in ``runner_main``
+in the switch::
+
+ case task_type_cooling:
+ runner_do_cooling(r, t->ci, 1);
+ break;
+
+
+Finalizing your Task
+--------------------
+
+Now that you have done the easiest part, you can start debugging by implementing a test and/or an example.
+Before creating your merge request with your new task, do not forget the most funny part that consists in writing a nice and beautiful documentation ;)
diff --git a/doc/RTD/source/Task/index.rst b/doc/RTD/source/Task/index.rst
new file mode 100644
index 0000000000000000000000000000000000000000..e701e924a79f9256d4c0b034b6c15651f41ff405
--- /dev/null
+++ b/doc/RTD/source/Task/index.rst
@@ -0,0 +1,21 @@
+.. Task
+ Loic Hausammann 17th July 2018
+
+.. _task:
+
+Task System
+===========
+
+This section of the documentation includes information on the task system
+available in SWIFT, as well as how to implement your own task.
+
+SWIFT produces at the beginning of each simulation a ``dot`` file (see the graphviz library for more information).
+It contains the full hierarchy of tasks used in this simulation.
+You can convert the ``dot`` file into a ``png`` with the following command
+``dot -Tpng dependency_graph.dot -o dependency_graph.png``.
+
+.. toctree::
+ :maxdepth: 2
+ :caption: Contents:
+
+ adding_your_own
diff --git a/doc/RTD/source/index.rst b/doc/RTD/source/index.rst
index 888945a5c0101bb6f59b574a30f1f736ad134079..05c15c5a081cb03ae4e53c26bf6fe4e8dd78dfd5 100644
--- a/doc/RTD/source/index.rst
+++ b/doc/RTD/source/index.rst
@@ -20,3 +20,4 @@ difference is the parameter file that will need to be adapted for SWIFT.
Cooling/index
EquationOfState/index
NewOption/index
+ Task/index